"I am not so sure that PAYE is that clever and I would recommend the OP looks to do a tax return at the end of the FY if he/she does not normally pay tax at the Higher Rate. Just to be on the safe side"
PAYE should be that clever, as long as the code stays on a 'cumulative' (normal) basis but if the code gets changed during the year and gets stuck on 'week1/month1' ('emergency code') then the overpayment will get frozen to the end of the year. Depends how clever the person fidling with the code is! But that's unusual if, as pontius says, you've only got the one steady job, as the OP appears to have.
Whatever, a tax return shouldn't be needed (they're a pain the . . ), and unless you are dealt with under Self Assessment anyway all you need do is send your P60 to your tax office for them to check at the end of the year and they can do a repayment from that.
But, I agree, ALWAYS CHECK, the system isn't perfect!