You need to sort out what are the most importnat factors and how serious they are .
Homesickness= usual- most people get over it and thrive- if not consider whether being somewhere closer to home.-
Degree choice= yoy will be getting £45,000 into debt and 3 years of tour life., so make sur its soemthing you wnat and will enjoy or be able to cope with.
Uni= if its not the one you wnat, then consider a hap year and maybe retakes so you cna go soemwhere else.
You have had time to think about this.
The worst mistake is to go somewhere where you are unhappy for 3 years at a place you dont wnat to be in a subject you dont enjoy.
Most people deal with homesickness just fine. You have to decide if its just fear becayse its your first time away and you are naxious or whether its soemthing more deep seated. Talk to friends, your mum , teacher anyone you know who is sound and rlatively calm or has been to uni. If yopu quit do it witin 14 days.