Darren
I have also had great difficulty finding a PVC glue that is the equivalent of the HH-66 that the Americans seem to swear by.

I found that Kwik Grip Advanced made by Selleys does a pretty good job of gluing the clear PVC to the frame, but not so good for PVC to PVC. It goes on white and dries clear.

It still seems to be holding OK after a few weeks and 10 hours paddling but gluing PVC to PVC obviously needs something better.

I am still searching for the right glue and hope to find it before I need to replace my temporary skin which is only 0.1mm or 0.004" thick.

I will be watching with interest to see what ideas you are able to elicit from the forum.