http://www.thecyclecentre.com/
These guys are great, they are always really helpful.
I was chatting to Tom about finishing off my bike build, (of which none of the parts were from them) and I needed some headset spacers and wasn’t sure how many. He gave me a handful, told me to use what I needed, come back to pay later, which I did the following week. Whenever I need anything now, as long as its close to Internet price I will try to buy from them.
They also have time to talk about different options and set ups.
Tom has also offered to lend me a reverb to try.
Beeline are great, but don’t seem to have the same enthusiasm, mind you, they are always so busy they don’t have the time I guess.
These are the two shops I would try.