Hi guys, thanks for all the suggestions.
I've seen the Sheldon Brown site before and although I don't share his genius I unfortunately share the condition that he had, hence the need for a recumbent trike and electric wheel.
A couple of years ago I would have gotten stuck in, it doesn't look too difficult but my hands dont work to well and trying to explain it to the wife would just be asking for trouble haha.
I got a quote from SJS for £130 including the rim, spokes, tape and delivery which is resonable so I'm gonna go with them.
Cheers,
Martin.