I've got a ticking noise coming from the nearside (I can hear it when driving behind the glovebox area). I'll try bullet points instead of writing an essay...

Engine C20XE with F20 box in a Corsa (M-Tech shafts/hubs/mounts)

Noise is a clicking kinda noise (much like the noise you get from tappets when they haven't got any oil yet)...
Noise is related to wheel-speed. No noise when idling at standstill...
Noise changes, but does not disappear, when the clutch is depressed (becomes slightly quieter)
I've had it checked by a local garage... expert opinion: "the gearbox is bollocksed"
If I put any power down, or put the engine under any other load (climbing a hill etc) then I can smell what seems like the clutch burning, but I can't notice the rev's climbing any quicker -- if it's slipping it can't be slipping that much
Conversion was done last October with a brand new clutch from Vauxhall. The car has done around 3'000 miles since... (pretty sure I don't ride the clutch too lmao)

Any ideas of what to try would be appreciated. I was just going to change the box, but the slipping clutch has me a bit confused... It surely can't be anything else like thrust bearing if it is related to wheel speed?