Take it to Caterham Midlands or McMillan (which I guess is closer) for the Geometery checks.
As for Nitrons, Why? You are looking at £1000 which is a lot to spend on Dampers when you use it on the road. I would stick with the Billies. If yours are shot then you can pick some up Second hand (from those who are upgrading to Nitrons etc) for not a lot of money.
Gareth
Blue and Carbon 6 Speed 1.8 Supersport here