Hi no probs but I dont mind recommending here. Im actually in Yorkshire so my usual is my local Maidenhead at Beverley, but I often have a nose around other branches if I am out and about and see one and you often see some nice surprises. But if I am traveling my favourites are Wharf Aquatics near Nottingham and Pier Aquatics in Wigan, Pier is slightly more specialist but is an amazing, amazing place if youre ever in the area. Down south I have been to the Aquarium Design Centre in central London on Great Portland Street before and Im always impressed when I go there and I've walked past Wholesale Aquatics, dismissing it as a little LFS but then as soon as I was back on the train home I remembered the name, they have a good reputation and are known to stock nice fish, they are on Bethnal Green Road. Wildwoods which is somewhere in Middlesex I have heard is meant to be good, not sure if thats too far out though?
To get in touch with specific breeders though you are often best off getting into local clubs who often have surprising species in them, they also sometimes organise big orders from the big American people like Rapps - to get a shipment to the UK is a minimum order of £1000 so people often club together.
Let me know if I can help any more
Wills