Bushcraft4life, It's a crying shame you'll not be able to get to the Moot. This is exactly the sort of sharpening problem I'll be hoping to help folks overcome in my workshop there.
As Chris Claycomb has said, if you can stop off "en-route" and want to meet up with me (Milton Keynes) I'll happily sort the knife out for you and show you how to do it for yourself in future.
You CAN sharpen a convex ground blade perfectly well with a flat hone despite what some might tell you. You just have to understand what it is you are trying to achieve and how to do it. The mouse-mat idea should work fine for you though if you follow the tutorials on the this forum.
Bardster, I hope you'll be taking
lots of that nice abrasive to Wales ? I can feel some "swapsies" coming on....