do I have any chance of studying chemical/mechanical engineering without physics?

Yeah, with a foundation year. Lots of courses at good engineering departments available with a foundation year - Birmingham, Manchester, Southampton, Sheffield etc. I would suggest doing as well as you can in your current courses and going the foundation year route honestly as it's less chop and change (and since you'll need maths regardless, if you "restart" A-levels you could end up in the situation of either a) doing A-level Maths over three years or b) not doing three full A-levels worth of exams at any time, both of which can be an issue for some of the more competitive unis).

It depends on the university. Some universities have Maths and Physics as mandatory, other say Maths + a science, so Chemistry would've worked and others say only Maths is required. The ones that say only Maths is required typically do also say they will reduce the requirments if you take Physics (or another science).
The Top 10 or 15 universities typically require physics however very good universities such as Cardiff and Newcastle only require Maths. Like others said, for the best of the best, a foundation year would be needed. I wouldn't reccommend retaking your A-Levels just to take Physics though.

If i'm not mistaken, I can also apply to other unis after my foundation year if I wanted to right?

Potentially however there is no guarantee a foundation year at one uni will be accepted at any other uni.
A foundation year is not a standalone qualification and you undertake it as part of a full degree programme - you would be applying to e.g. "BEng Mechanical Engineering with Foundation Year - 4 years", not a 1 year foundation then reapplying to 3 year BEng courses elsewhere.
This means:
a) as noted it's not necessarily going to be accepted by any other university as it's not a qualification by itself, and it's only designed to specifically prepare students for the first year of the engineering course at the university you enrolled on the degree with foundation year at.
b) from a student finance perspective it's one year of your full degree, and therefore if you change uni after a foundation year you count as restarting your course from first year elsewhere and you will therefore end up using up your "gift year" of SFE funding on the foundation year - which can be a problem if you subsequently need to retake a year or change your mind again.
You should never apply to a degree programme (including degrees with an integrated foundation year) you don't intend to finish. Don't apply to the foundation year with the plan at the outset to try and "trade up" to another university.

I am doing a level physics, chemistry and maths as I wanted to study chemical engineering
. I know that content depends on different schools and unis but so far physics has not been too hard - if you feel like you can do well in physics I would suggest taking physics BUT most unis require you to have maths and chemistry for chemical engineering and some unis allow maths and physics/chemistry .
Chemistry however has been a bit difficult to understand, so do plan according to that
I would also suggest you drop business as chemical engineering is a rigourous course and some unis don't particularly like business A Level (idk why)
Foundation years are really good too , but leave it as the last resort. If you are changing subjects then make sure you put in the hard work and utilise the upcoming Christmas holidays to your benefit.
Overall, make sure you don't regret your choice because at the end of the day , STEM subjects are difficult especially in Year 13/A2

Basically before the start of the year I had picked maths, chem and business. However I stupidly decided to switch out chem for law (should've swapped out business for law) because I got scared about doing chemistry. At the time I didn't realise that physics was a key requirement for engineering at uni and thought that maths could be enough.
Today I spoke to my head of physics department in hopes that I could swap business for physics but he told me the deadline was 6 weeks ago. I now don't know what my options are other than to A) restart the entire year making me 2 years behind because last year I studied abroad since me and my family moved elsewhere or B) pray that i'm able to do a foundation year at the uni I want and continue from there. I was wondering if anyone had any suggestions on what to do? My tutor will likely ask me tomorrow whether I was able to switch or not and hopefully we can discuss it further then.

thank you for your input and advice. I would really like to switch but the head of physics told me that i'm 6 weeks late to the deadline so i'm not sure if they'll let me anymore unfortunately. I didn't really put up a fight when I had a conversation with him earlier today because I thought it was final (and it may be so). The reason I want to do physics and not chem is because physics seems to be more versatile in the sense that if i change my mind on chem engineering then physics will likely get me further than chem (or so I believe). I really hope they give me a chance to switch but I guess i'll find out in the following days.