Don't like being at sixth form and gradually withdrawing (Anxiety/Depression)

, I'm seriously thinking of changing sixth forms because I don't like my other sixth form I'm at and in particular I'm hating Biology. Because of this, it's causing troubles for my other subjects by making me more tired than usual (Both mentally and physically) I didn't anticipate until now how much it would negatively affect me in the long term. How i performed in my mocks due to fragmented sleep and having to travel to another town, I thought that this would impact my performance as well as being depressed by the environment as I don't enjoy being there. I dread waking up everyday for it. I'm in year 12 right now and I'm currently doing (Maths, Biology and Chemistry). I wanted to do Further Maths as a 4th choice but I wasn't allowed to take it despite I met their requirements for it. The other sixth form, I'm wanting to take Maths, Further Maths and Chemistry as I want to study Maths at uni. My current exam board is AQA for all three whereas for the other sixth form I know it's different. I've called the sixth form up and they said that they'll consider my application and everything and they also said that I may have to restart the year or continue. I've also got depression and anxiety which makes the situation worse. If I were to get into that sixth form, and have to do the year again, will it put me at a disadvantage?

I don't think it would, it may even become an advantage - you'd start again but you may know some of the content, therefore it may act as a revision class until you start something new. As for depression and anxiety, I think it just depends on how you deal with it - a close friend of mine has depression, but she's set herself a routine and she's doing fine right now, if at the start of the year she was struggling (we're both in yr 12).
Hope this has helped

Absolutely not mate.
By the sounds of it, you'll really regret staying at your current sixth form since after a tortuous 2 years, the grades you achieve will not reflect on your true potential.

Just remember, in the end of the day it's about 'what qualifications you have to apply for the course you want to do at university'.

You may think that your friends are too important to allow you to restart, but that isn't the case at all. From personal experiance I can assure you, out of your 300 friends in school, you'll come out with only a few that you actually contact years later. Your real friends will be in university, as everyone in the same university have a similar wavelength so you'll get along with them in the coming years.

I'm planning on going to a different sixth form and it may be that I might have to restart the year in which I don't mind or they'll accept me in this time of the year and I basically catch up so I can do my AS in maths and restart the year for Further Maths and Chemistry which I don't mind to but it's better that I go as soon as possible. I'm just worried whether universities will mind that if I do another year but I had only changed courses (Bio to FM). I just gave in my application to the sixth form that I want to go and they did say that they will consider it and will give me a reply I think the Monday or Tuesday. I also did mention my circumstances I am in right now so yeah.

They wouldn't worry about that, only that you got the grades they wanted in the course you want to take. Age shouldn't matter as many people go to uni at different ages, and you don't have to put on your CV that you even changed Sixth Forms if you don't want to, and your situation that you're in shouldn't affect what the uni thinks of you anyway.