Hi there 😊
It is great that you're thinking about what you want to study at university already!
So majority pharmacy schools in the UK require chemistry and biology is a great complement and is highly recommended. For your third option, I would advise picking something you enjoy and you'll do well in.
Then when you're in Y13, you submit your application on UCAS (university application website) and you get to pick up to 5 pharmacy schools. Then hopefully you'll get offered an interview and then offered a place to study at a university. You will spend 4 years studying the MPharm degree and once in your 4th year, you have to do Oriel (an situational judgement and numeracy exam) to get a foundation year programme. You will then complete a year in the sector you have chosen which is also known as a pre-reg year. After working for a year, you'll be able to sit the GPhC exam which allows you to qualify as a registered pharmacist.
When looking a universities, I would say look at the type of campus vs city, course structure, assessment, social life etc.
You've put yourself in a great position so best of luck!
University of Bath