As someone who last minute switched to do A-Lev Maths, Chem, Phy and Bio, if you don't like maths, don't do it. It is sure an important subject, but if you're not managing it's not a good option. For maths in physics, it relies on clever manipulation of equations and explaining with equations. Also, you learn AS and A2 applied maths in AS physics, whilst the applied maths in A2 physics is far beyond A-Lev maths. So, don't do physics or maths unless you don't have other choices.