undertheweather
If you fail the NPPL medical you've still got the option of a FAA PPL with the FAA Class 3 medical. Talk to your AME - some do FAA medicals too, otherwise (if you fail) find one which does and talk to him.
With an FAA PPL you can fly a G-reg in the UK, and others here will say that you can do so worldwide. The NPPL is a bit of an irrelevance once you know about the FAA route. You just have to travel a little further afield to find a place where you can do it (UK).