[murphyv310]

There were a number of UK made sets that used the AW53-88 and I am sure you will get one here. They were used throughout Europe and were quite common.
The "Miniwatt" is a Philips tube and sold here as a Mullard.

There are other CRT's you can use EG Mazda CME2108 will work with the exception of the 12.6v heater, which would be fine in a series connected heater chain, or a 2:1 transformer in a parallel circuit.