Hi Paul .
It's important that you get a full HPI check ,the ones that autotrader offer are ideal at £25 for 5 checks ,or £20each .
Don't use the text check type ,they exclude a finance check .However they are cheap at £3 .
You should also do an mot history check which is free ,it will help to confirm a cars mileage .The check is on the direct gov site , you need the reg number and the v5 document reference number,or the mot certificate number .
Paul, i was confused as to which site to go to when buying my used car, the best site i found that gives you a comparision as to what you get is .carcheckdirect.co.uk. tells you exactly what you will get