The engine code in either the service book (inside front cover) or on the engine on in the boot around the spare or even on the V5 but the DVLA are a bit rubbish sometimes.
You are looking for APY, AMK or BAM for a UK car, APY and AMK are 210 BHP(154kw) and BAM is 225BHP(165kw).
you could also have a look in the FAQ at the top of the forum, there's some useful info.