Hi,
I visited the MA at St Albans a couple of months ago and was a bit underwhelmed - can't really put my finger on why. Some reasonable shrimp from memory, lots of unusual wild caught fish and a very impressive reef tank. Almost too big!
Wholesale Aquatics - do you mean Wholesale Tropicals in Bethnal Green? If so, large selection of fish, some incredible value ( I seem to remember amano shrimp were £2 each for example - compare that to most Maidenhead Aquatics). Tanks are fairly spartan, dimly lit though - so fish aren't often shown at their best. Must be doing something right there though - I first went 27 years ago!
Surrey wise - my favourite is the Maidenhead Aquatics in Addlestone/Weybridge. Very friendly staff, impressive range of fish but only sell red cherry shrimp.
A little further away is The Fish Barn in Crawley. Some of the best fish going, very friendly staff (father and son business - mostly the son). Not very big but the prices are very good. Was in there yesterday - a bit low on shrimp and plants but some nice nano sized fish in stock - raspboras etc. Also have a small but good range of hardscaping materials (sorry - I meant to reply to your hardscaping thread the other day).
If you head to Crawley, you could combine it with a trip to:
World of Water, Crawley. Not been but looks like they have a good selection of fish -
http://www.aquarist-classifieds.co.uk/php/detail62_324415.php
Aquatics to your Door - only a few minutes from The Fish Barn
and of course the Maidenhead Aquatics in Crawley itself.
If you were to wait a few weeks the new Aquatic Design Centre should be open soon. The old central London store was one of the best places for shrimp and nano species.
Regards, Mark