Hi, I don't know about biology or medicine as I've only just finished my AS exams and will be applying for Physics.
I recently attended a summer school at Newcastle Uni, and I think you made a great choice with Newcastle. The city is consistently rated as one of the best (usually THE best) student cities - you will definitely be able to develop as a person. Everyone is so friendly, especially compared to London (in my opinion) - there's a reason London unis tend to have lower student satisfaction than pretty much everywhere else in the country.
Newcastle is also more well regarded as a university than UEA, but both universities are good either way.
However, your personal well being should ALWAYS come first, but you may be able to get mental care whilst at uni - do some research into that.
Good luck with everything, hope everything goes well!