Dom McNeill,
If you have A-level physics... you should breeze the science/maths entrance tests.
You also need a class 1 medical before you are accepted on to a course which you have to undergo at Gatwick airport.
Finally the biggest hurdle for anybody not born with silver spoon in their mouths (if you did then good for you!) is the money.
I worked as a programmer for 4 and a half years to save up for the minimum 50K (Include accomodation / food and any resits on top of this). The last thing i wanted to do was take out a loan from HSBC and pay 50K + interest whilst under the pressure of trying to find employment. It took an eternity to save up but at least now i am not under any great pressure to quickly find a job and have 4+ years of IT experience to fall back on.
However please dont let that put you off. If you want to become a pilot anywhere near as much i do then do absolutely everything to achieve your dream.
Good luck mate.