A level biology is a good choice - it opens you up to most allied health professional degrees such as Radiography, Physiotherapy, Audiology, Paramedic Science, etc. I just searched up the entry requirements of architecture at BCU and they list preferred subjects: Art and Design, History, Geography, English, Languages, Science or separate Science such as Physics, Biology or Chemistry, Sociology, Philosophy, Psychology, Maths, Music. Since you have picked geography and biology this will definitely help you apply for an architecture degree. Another choice I would recommend is a level economics/business studies because these allow you to apply for a broader range of degrees such as Accounting, Finance, Law, Human Resources, Business Management, Economics (BA), etc. By picking these three choices you are widening up your options, however, it is to be noted that most business school courses do not require any specific subjects most of the time except for some universities (normally Russel Group) that are mathematically intensive with their degrees so best to check up on that - sometimes they require a level maths or a 6/7 in GCSE maths. You want to take a soft subject as your third, I have done a level biology (got an A) and it is very very heavy and consumes a lot of time and I'm sure geography is hard in it's own sense - therefore doing a level business is a good choice as it's much more relaxed. A level psychology is also very heavy having done it, it involves a lot of memorisation and essay writing. Hope this helps, if you need more information let me know!