Leaking head gasket

[Sugar Spun Sisters]

Following on from my previous 'brakes' problem, the mechanics have reported that my near side and off side head gaskets are leaking slightly.
I know this could be a major problem, but how much of one at this point?
I have had the van for 18 months and have always had to top up the coolant after most journeys, usually the amount is 2cm. The amount of coolant lost hasn't altered...it's a familiar pattern.
I had a compression test which didn't show anything up. That was about a year ago, but clearly the gaskets were not leaking then. The van has never overheated since I have owned it, but I found out the previous owner didn't really take much care with the coolant side and had a problem with overheating a year before I bought it.
What is the likelihood the gasket is going to blow soon?
Is it a a case of 'how long is a piece of string?'
What is the likelihood that I will need a new engine? I understand the corrosion of the head bolts being a problem.
Any thoughts on this topic is much appreciated. We are due to go to Snowdonia this weekend for a 2 week trip, is it advisable to head off into the mountains?

[ermie571]

get an AA card, take it gently, and go, watching your guages, checking your coolant and bleeding your rad.
How long? who knows
Am in a similar postion....only mine has gone to the next stage....now got exhaust gasses in the coolant....
Just don't tell the AA you knew it was on the way....

Em
xx