rac3r

Here are some prices I got

Maxton:
GP20 Cartridge kit fitted with new oil and seals. Adjustable for rebound damping only £560 + VAT
SD25 Cartridge kit fitted, fully adjustable £675 + VAT

Brook Suspension:
Andreani Cartridge kit £650 fitted (£500 without fitting) includes springs for your weight
Nitron Sport shock £438
If you buy both they will take 10% off the shock (£394.20)

I think I'll go with a cartridge kit and shock because the fork swaps are too complicated! I ride for fun and tend to cruise a long more and more rather than full attack so I think this may be the best