Hi Oliver. Don't think that we are ignoring you [
], it's just that we don't know what it could be (and it is bank holiday weekend so everyone is probably out enjoying themselves).
It's difficult to diagnose what a noise could be without hearing it, or also exactly where it is coming from. Is it from the suspension, the engine, front, rear which side etc. Does it vary with speed, go away with the clutch pressed? Is it worse on bumpy roads?
The gearstick has a rubber boot inside the leather gaitor which stops outside noise getting into the cabin. It 'could' be that yours has split causing the gearstick noise.
CV joints are either end of the two driveshafts that come out of the gearbox and attach to the rear wheels, so you have four. If you look under the rear of the car you will see both driveshafts have a rubber boot at each end, the CV joints are inside these rubber boots. If the clunking is a CV joint then they are about £130 plus an hours labour to fit, but some people have had success merely repacking the boot with fresh grease or turning the driveshaft around so the worn joint is on the other side. IE the joint next to the gearbox is now next to the wheel and vice versa.
I would seriously recommed you get a mechanic to look at it straight away if you intend to go down to Le Mans in it. In my limited experience things don't get better by themselves, but it could be fairly minor so better to fix it straight away before it damages something else which could be £££££'s (don't ask me how I know this [
] )