The big question would be what are the duties and taxes to be added on top in order to ship to the UK. You'd probably have to contact each vendor and find out. They also might have a dealer in the UK who can sell to you directly.
If I'm not mistaken, the GM360 is the Euro equivalent of the US CDM1550 so yes, any URI/RIM should work. Just a matter of programming the accessory port and codeplug correctly.
The RIM_Maxtrac will plug directly into the rear of the Motorola Maxtrac/GM300/CDM series radio. (with the radios with 20 pin connectors, plug it into the center 16 pins)
More info here: Repeater Builder USB-RIM Lite
scroll down on the page to find the RIM_Maxtrac.