Cheers for all the help guys, really appreciate it.
From what you've all posted it seems I'll try a BMX freewheel but my best bet may be to buy a cheap rear SS wheel or one with a proper free hub if the BMX route doesn't work. Re-dishing the wheel shouldn't be a problem, I've recently built my first proper wheelset so have a little experience already.
I'll have a sit down and will go throught the 3 sites recommended above too.
@meehaja Cheers for the offer but that's about £120 more than I wanted to pay 😆
@Hairychested That's definately cheating and I love a good project 😀