I will check on Monday if there are some water pumps left in the store - new, and write about price and delivery.
Send a pic of the water pump to see if it is the normal truck-version!!!
Impeller comes with bearings and you will need a set of gaskets. better a complete pump if available.
spares are getting very rare as they are clearance items and Russian parts have become expensive even above EU levels.
There is an import duty and VAT on them. Most GAZ 53/66 trucks have been converted to Mercedes Diesel engines or scraped, gas prices are EU level...why drive a truck that drinks 22-40lt gas /100klm?
You need only normal A95 pump-gas not AVGAS. This is a low compression engine it you will have ignition problems with AVGAS, mix it at least 50/50 with pump-gas.
Probably it could be send by courier-service - DHL or like. Where to be send in the UK?
Christian