inferiority complex about uni?

There is two parts to this in play here I can see.
Firstly, if you're not satisfied with a particular institution, then do not attend there. Medical school is hard enough, let alone if you knowingly enter it on the back foot or with the mindset that you're automatically going to be dissatisfied by being there for no other reason other than the location. That's a recipe for several years of grief, I can tell you that.
Secondly, you're going to need to adjust your mindset a little I think. No magic doors are going to unlock in the world of medicine purely because you attended any particular institution. You are going to graduate eventually at the same time as and alongside several thousand other people who will have the same letters after their name as you. You will not be paid any more nor given priority in any respect at post-graduate level based purely on anything you achieved whilst in school unless you have managed to write some high impact articles or been involved in some other extracurricular project which, as anyone will tell you, takes some doing and in reality these may be completed by virtually anyone at any medical school in the world.
Also, in respect to feeling inadequate: you need to totally remove that thought from your head straight away. You are going to meet an entire boat load of people who have been to a variety of institutions and completed some pretty amazing things. I can't remember the exact details now but I recall meeting a consultant who had completed their training at a relatively young age, conducted a pretty serious PhD somewhere along the way and completed thousands of a particular tricky procedure before they decided to do some teaching for us basically as a change of pace and to make them a better boss. They had figured that to better understand the trainees they had working under them they would benefit from experiencing medical school through the eyes of brand new students. And this is a far from isolated example in my experience.
My point is that there is literally no real bandwidth to have that kind of thought process in your head- if you think you're going to feel inadequate merely because you attended X instead of Y, the world of medicine is going to be filled with people who have done pretty fantastic things which you won't yet have done. The UK isn't the be all and end-all of medicine, either. People attend Harvard. People work for eminent surgeons and researchers worldwide. One nurse I worked with showed me a hospital they worked in abroad. It was world-renowned specialist centre for particular procedures and had more than 4000 beds. There isn't anything remotely like that in the UK.
In summary, you need to attend a medical school that is a good fit for you and which ticks as many boxes as you want ticked. If Oxford or Cambridge suit you because of their teaching style, the settings, the history, your friends are there etc etc etc, those are totally legitimate reasons to attend a particular place. But don't go there purely because you think another institution is less prestigious or you feel you will be looked down on because you attended it. If someone ever expresses negativity toward an individual merely because they attended some particular medical school, that's not a good thing in my view.

thank you, this is some very good advice that i will definitely take into consideration. i think my view of things has definitely been a bit narrow-minded. i plan to think about what matters most to me when it comes to picking a medical school.

i applied to med this year, and received two offers both from russell group unis. one of the universities i was rejected from was cambridge (post-interview). in truth, even though i was fortunate enough to receive offers for med, i am still not fully over my cambridge rejection and i am overall a bit dissatisfied with the other unis i applied to.
i put a LOT of time and effort into my cambridge application, in terms of doing lots of specialised super curriculars and wider reading to prepare for the interview. my ‘stats’ were near perfect (gcses all 9s but 1, 92nd percentile in the UCAT, predicted 3A*s). even though there were moments in the interview where i floundered, i thought at the time that they went ok. ultimately though, i was rejected.
as someone who has been labelled ‘the smart one’ throughout the entirety of their time at school, this was devastating. i learned that i had in fact, made academic validation the source of all my confidence. with the pre-interview rejection from a high-ranking russell group for medicine the previous week i was left waiting to hear from two others.
in that time, i’d begun fixating on the fact that i hadn’t applied to ucl, a university that i was sure i could have gotten at least an interview from, comparing my stats to people on reddit (ik bad idea). i did eventually get offers from the other two universities, and i am very grateful for this.
however, after seeking out a university like cambridge for so long, i realised had become obsessed with the prestige and the name of the university i was going to. the university i have firmed is still a russell group, however a part of me still thinks i should be going somewhere better. i unfortunately do care about how my university is viewed by my peers and my teachers and even though i KNOW its not a bad university at all, i still feel like i have failed in everyones eyes by not going to oxbridge or london.
i am aware that this is a very silly post, and that medicine is very competitive and that i am very lucky to have received two offers. but does anybody have any advice with dealing of feelings of inadequacy and moving forward after rejection?