Quick update,

I found these guys just over the border in Germany who do a nitrogen gas pressure test and are open all day on a Saturday. FYI this is a much more reliable method of checking for leaks by comparison with a standard vacuum check because the system is pressurised in excess of operating pressure.

http://www.autofullservice-danner.de/

Total cost was about EUR150 and the pressure test was EUR60.

The guy shook his head when I said I had changed the condenser myself, so it was a great feeling to be told it didn't leak! Plus I now have glorious cold air in my car!