tyre time

[mtread]

Then I'd probably let them fit em on the bike, then check chain adjustment myself afterwards

So do I !
As I'm on the opposite side of London I normally go here http://www.motorcycletyresuk.com/index2.htm They are quoting £208 + £50 fitting the pair, although they do seem to be offering £30 off at the moment.
If you like PR2s you'll like PR3s even more. About an extra £30 for a pair