No idea what you are on about with the 25% though. bitstamp.net is very efficient, just a £9 charge to wire money to them with SEPA transfer. Give them a go. Its only 25% if you want to deposit £40 or something 
Do your math on deposit of 4000£ it is not that bad suddenly. UK exchange is not an easy proposition. You either be a cowboy like intersango and do it ignoring all the laws and get shutdown as soon as you get some volume or you do it by the book and basically dump half a million GBP into getting FSA registration, which you still will not get because FSA refuses to regulate Bitcoin exchanges as it is "not money". But if you do it without FSA license you will get shutdown by banks.
Only way in UK it seems is for a well established in financial services player to start trading Bitcoin on the side. So gotta wait until this happens.
Damn you FSA ruining everyone's fun
Ok what about creating a site like localbitcoin that's prices reflected the main exchanges more accurately?