Sorry, I didn't notice the kit that I linked above is the 350w version. You must get a 250w motor to be legal, which, of course, is out of stock. That's why they're pointing at the cassette version. A cassette version will work OK. It's just that the freewheel version would have been slightly better if you could get one.I see, part of me thinks the cassette sale might be due to returned kits they are trying to re-sell, but I could be wrong. Thanks for your advice mate, I'd rather go for an option with less issues when it is within my means - have requested cancellation of the cassette version.
As for that clip, that's crazy, goes to show that the ones with the mechanical know- how aren't always the ones on screen.