It's gotten harder to buy btc in the uk in a reasonable amount of time after mt.gox stopped taking cash deposits and intersango's had their uk bank closed 
Have you tried Blockchain.info's new Pingit purchase method? It gets pretty heavy use now.
Have you tried Bitcoin-Central?
Tried setting up the pingit service however I never recieved the penny deposit with the reference code - and if you try and call the help line, you get put through to a call centre in india, with a horrible, horrible connection, so it's basically impossible to get anything sorted out.
I've not tried bitcoin-central however