Those subjects are fine, do what you want (obv including bio and chem), because it will make your life so much easier. I picked maths, because I quite liked GCSE, and I was told it was a 'good subject' to do, it was a complete nightmare. If I'd chosen something I really wanted to do, it would have been a lot better and less stressful. What matters is that you get the grades, and an A in sociology or whatever will help so much more than a lower grade in maths/physics. There is no need to do extra sciences unless you want to.
Really try and get a B in maths gcse, some places will accept a C, but having a B just gives you more options. If you dont get it though, its not the end of the world.