I'm not going to lie, as a finance professional, I'm really surprised you offered full asking price.
If it does come back that the place needs any rewiring, boiler work, etc., ask the seller to pay 100% of the estimated costs - not 50/50. They are lapping up the cream with a full asking price offer. They would NOT have been expecting that.
Also ensure you go for a PREMIUM INDEPENDENT surveyor and NOT the one required by the mortgage lender. It'll cost a couple of thousand pounds but will be money very well spent.
I was sort of surprised as well. I guess if the price was already discounted and other people had made offers at asking price then fair enough, that's the price. But if the price is not already cheap for the area, and work actually has to be done, and nobody else went up to asking price, then the sellers must be celebrating.
If you get a complete survey like KFDancer is talking about and it actually does point out serious problems, then you can use that as an excuse to lower your offer. Or you can just pick out something not so serious and still lower your offer. It works out better that way because then all those other offers have faded away. Don't feel guilty at all for changing your offer at any time, believe me, the sellers will do the same to you given the opportunity. Trust me, the estate agent is showing that house to other people right now, telling them your offer and suggesting they top it.
You've got the advantage because British people are the worst negotiators on the planet! As soon as you start talking about money in public, they freak out and will agree to anything to get you to stop.