Your local vet is the person to ask in addition to their own service they will know of any private service providers in the area.mine has leaflets in the waiting area for all animal related services.
Unfortunately there doesn't seem to be any pet crems in Wales that belong to this association. The nearest one is Pucklechurch, Bristol/Bath way. http://www.companionshaven.co.uk/
I am near Swansea and used companion haven in Pucklechurch. We took Taryn there on Saturday to the chapel of rest. I have used them before and they are excellent.