My Vrs has started to drink coolant,at the moment it goes from max to min in about 3 days (30miles) there is also plenty of mayo under the filler cap,I am hoping this may be just the short journey/cold weather.

Anyway the car is booked in at JBS auto tomorrow for a chemi test to see if the head gasket has gone,what sort of cost should I expect to pay if this is the case?

Car performance seems to be fine.

You could check the appearance of the oil on the dipstick? The mayo on the filler cap could just be from the cold weather. The water connections at the bottom of the radiator are prone to leakage so you could have a look there perhaps.

as above, i'd say the mayo was from the short journeys you've been doing,

i'm guessing there will be a leak somewhere, so JBS should also do a coolant pressure test

I just found this picture indicating what head gasket failed oil looks like http://i27.photobucket.com/albums/c162/veritamortem/DSC01208.jpg

No mayo on dipstick so i suppose thats a positive