Thanks, i think any degree can be difficult but if you put the hard work and effort in then it will pay off.
I have friends who have applied for (and are going to study) economics with alevels in maths, further maths and economics. It will definately equip you for atleast the beginners level of maths in economics i think. I think physics has more to do with the mechanics modules that are available in the A level maths syllabus. But it really depends on you, I think you will still need to do a few mechanics modules with further maths but you are also able to cover the further pure modules as well which are important in Act sci.