objective insight please :)

Hi all! this is going to be long winded- but I would love some objective insight. Please share your thoughts! bare in mind I will eventaully make my own decision but really want to know what other people my age think.
I'm 20 years old. I have a history in art, sociology, and language in my a-levels, all between A*-B. I completed a foundation year in Graphic Communication, and I have been working in an independent restaurant ever since- in both a managerial FOH role, and marketing team/manager role (we are a very small team, I basically did all the social media etc.). I planned to go to university this september, a mid ranking university (lower end of top 50 in league tables), and in the top 20 for Marketing. This is to study Marketing/management with psychology. Now, half of me, is very excited, and I look forward to studying it, and, I know I will make the most of it- applying for internships, having a placement year, taking on my own projects... however the other half is super apprehensive, and is wondering whether I shouldn't go, or defer.
Career wise- there are so many positions I would like to be in. The overarching practice I would enjoy is an intuitive/investigative/analysis role, whether it be HR and delegating particular roles, or marketing research and trend analysis, or working with the police as an investigator (which I know having a criminology degree would be a no brainer, but I really dont like the thought of being a 'bobby on the beat' for a couple years before, which is necessary...) Or, be a part of a large company, and be on the international/external affairs team. I would love that. This is why I think my chosen course is quite good, as it is multifaceted, in that I have psychology, management and corporate marketing.
I think the biggest factor is knowing I could probably get a place in a higher ranking uni- especially if I spent another year gaining more experience and shadowing people in the industry? Another part of me wonders whether this course even is for me. I speak French and English fluently, and am currently learning another language, a skill I feel very passionate about. I wonder whether I could use these for an entirely different career path (not interpretation! but external affairs) I have so many fleeting interests- criminiology, linguistics, law and governance.. but I know marketing is a fairly lucrative industry, and if I really do not enjoy it, I can use the psychology minor to divulge into another field- criminology or such, if I use it correctly. I also don't want to move very far from home, for many reasons, so realistically will only be looking at universities on the south coast to London.
I'm really stressed as I know the start of term is only around the corner. University is certainly something I don't want to waste, in that I have chosen the wrong course/university. I would like to know if anyone has had a similar experience, or are in the same boat. The most logical option in my mind is to go for it as planned, and, if I dont enjoy it, I can drop out. I know how excited I was at first, so there was evidently some passion there. Or, I defer for a year, explore my passions, try and get some experience in industries... What does everyone think? I really appreciate any feedback. Thank you everyone!
Another question- has anyone had experience with interning/shadowing in a range of fields without a degree, or any relevant qualifications? I would certainly be willing to commute to London.

Since you want an objective insight...
I have a history in art, sociology, and language in my a-levels, all between A*-B
OK
I completed a foundation year in Graphic Communication
Why? I thought Graphic Communications is a subject where they don't require you to have specific subjects and most don't ask for high grades.
This is to study Marketing/management with psychology.
I don't see the point of doing the marketing/management degree. If you want to go into psychology, doing a BPS accredited degree would be useful, but this isn't what you said you wanted.
Now, half of me, is very excited, and I look forward to studying it, and, I know I will make the most of it- applying for internships, having a placement year, taking on my own projects...
Networking, please do network.
however the other half is super apprehensive, and is wondering whether I shouldn't go, or defer.
If you have second thoughts, then almost always by default you shouldn't.
The overarching practice I would enjoy is an intuitive/investigative/analysis role,
OK
whether it be HR and delegating particular roles, or marketing research and trend analysis,
These roles don't require degrees. If anything, I would do the professional qualifications for them - cheaper, more widely recognised, and quicker.
or working with the police as an investigator (which I know having a criminology degree would be a no brainer, but I really dont like the thought of being a 'bobby on the beat' for a couple years before, which is necessary...)
As far as I know, you only need A Levels to join the force. If you have a degree, you can fast track your way to become an inspector. Even then, a degree in criminology isn't requested. The degree of choice is a degree in policing - the job is more about enforcement than anything else, as far as I know.
Or, be a part of a large company, and be on the international/external affairs team.
As in PR? Again, no degree required and professional qualification preferred.
This is why I think my chosen course is quite good, as it is multifaceted, in that I have psychology, management and corporate marketing.
Meh. I would get a second opinion from the police/inspectors, marketers, and PR people. I'm somewhat confident that they would echo the above opinion though.
I think the biggest factor is knowing I could probably get a place in a higher ranking uni- especially if I spent another year gaining more experience and shadowing people in the industry?
So you're looking to resit your A Levels? Gaining more experience only improves your personal statement and showcasing your passion for the degree that you intend to study in terms of uni application. Gaining experience and shadowing does really help with job applications though.
I speak French and English fluently, and am currently learning another language, a skill I feel very passionate about.
Awesome. Which language do you intend to study? Do you use specific methods for learning languages?
I wonder whether I could use these for an entirely different career path (not interpretation! but external affairs)
Yep, but mostly for front facing roles. You're ultimately interpreting in one aspect or another, but if the language is in demand, you can sometimes use it to liaise with clients or your colleagues in international offices. I would bring this up in MNCs that you intend to apply for or for roles that specifically require you to be fluent in the language that they need.
I have so many fleeting interests- criminiology, linguistics, law and governance.. but I know marketing is a fairly lucrative industry, and if I really do not enjoy it, I can use the psychology minor to divulge into another field- criminology or such, if I use it correctly.
In which case, I would probably for an LLB with a language (LLB as opposed to a BA, otherwise you would need to jump through extra hoops for roles in law). You can always do a postgrad in psychology, linguistics, criminology (sometimes), marketing, or management.
Having said that, you can also do a PGDL with an undergrad in any of the above.
The subjects where you either need a degree or benefit in your application by having one are in criminology (ideally with a lot of quantitative modules), law, linguistics, and psychology. Other subjects aren't really required or you can do better with alternative qualifications.
Note: I have not seen postgrads for specific languages, so your best bet is usually doing them in your undergrad. Having said that, I would rather do the official language certificates over a degree in the language. See: https://en.wikipedia.org/wiki/Common_European_Framework_of_Reference_for_Languages#Language-specific_scales
I also don't want to move very far from home, for many reasons, so realistically will only be looking at universities on the south coast to London.
You might have problems finding higher ranking unis in your area then.
I don't want to waste, in that I have chosen the wrong course/university.
Since you don't want to waste your degree (funding from Student Finance is limited to your first set of qualifications under the ELQ policy - unless you're telling me you're loaded and can fund everything yourself), you would want to look at the limiting factors based on your range of chosen subjects.
I would prioritise law and psychology as the main subjects of choice to do your degrees in since they are the domains where they expect you to have a degree. Criminology and linguistics are specialist areas you can go into research with, but they aren't really required degrees outside of academia for any particular job role. You can always go into PR, marketing, or policing with any degree or no degree at all; I don't see them as the priority unless you intend to become a lecturer in the subjects. However, it's up to you what you pick.
I defer for a year, explore my passions, try and get some experience in industries...
If you intend to work in industry and you want to use your degrees to get into specific roles in industry, I would strongly recommend this. You would quickly realise what works for you and what doesn't - something you can't find out by reading and studying. I would ask a lot of career related questions with the people in those roles (ideally with 5-10 years' experience in the industry); they can tell you more than what most teachers and lecturers can.

Thank you for such an indepth answer! I did graphic design/comms as it was a pathway from an art+design foundation. I am very keen on networking, I'm going to start looking for events. As for professional qualifications- do you mean CIPD/CIPR approved courses? Or whichever are relevant to the field?
I'm not looking to resit my a levels, just improve my personal statement.
I'm learning Dutch at the moment- for personal sake really, as I the majority of dutchies speak English very well. I plan on learning Spanish afterwards. I think I have good methods of learning.
I will absolutely be relying on student finance so this is also a good point.
I am not planning to become a lecturer either. It would definitly benefit me more if I held a degree that is more expected for it's industry... Thank you for pointing this out. All these points have been very useful.
I really appreciate all of this!