Don't take what the Guage says as gospel mate, if in doubt, check the dipstick. If it had gone down dramatically look at the usual areas and drive/road to see if there's a leak
Cant wait to see this at Curborough if youre taking it!!! How much was your cage done by them if you dont mind me asking. I know it wont be the same as the cars are different its just to get a rough idea of costs
Cheers