Have you considered getting Blockley supplier MWS in Slough to fit them? Not too far for you and at least they know what they're doing. Failing that, you may be better off finding a sympathetic motorcycle dealer/tyre fitter.
Just did that today (and in the wet!). Surprised at how big an operation MWS is. Avons had last 10K miles but it was time for them to go - the ride seems a bit better with some beefy tread on the tyres!
