Maths, further maths and chemistry are very good choices that open up a lot of possibilities. Physics is only required for Physics or Engineering at university, and a few of the top universities like it if you have Physics but are applying for Maths or Computer Science. If you think there's a strong possibility that you might want to do medicine, you should take Biology (but remember many medical schools don't require biology so the medicine route isn't completely closed to you even if you don't take it).
If you aren't considering a degree in physics or engineering (or maths/CS at the very top universities) there's no need to take Physics unless you want to take it because you enjoy it.
It really depends on which of the subjects you think you'd enjoy more. The physics A level isn't very mathematical (there's only so much maths they can put in without making the subject inaccessible to those not taking A level maths) as most of the 'maths' is just plug-and-chug calculations. However it goes very well with Maths and FM and can really help with the mechanics topics in maths.
I dropped biology at the end of the first term of year 12 so I can't speak for the rest of the course, but biology is heavily memorisation based and can be a bit of a content overload at times (think back to all the GCSE biology long model-answer sentences you had to remember - it's a bit like that but with far more content). The topics are quite interesting though, and if you're strongly considering medicine you should choose it. Do remember that many medical schools won't make offers that include both Maths and Further Maths.