Great choice of cage
Whereabouts in the UK are you?
They are available at certain online stores but you may now have a better chance of finding them in a local petshop known as the
"Montagna Criceto Rex". I've no idea why the name has changed but I'm in Leicester and there are three local petshops that stock them and they all now have them labelled as Montagna. If your local petshop hasn't got them they might consider ordering one for you - mine does that.
I can't find any online or on ebay - maybe someone else has a link??