Hi David,
The quiescent drain for our cars is 30 milliamperes or 0.03A so not very high at all. This is also easily checked.
I would ensure the day before you leave, you allow your CTEK to fully charge the battery. However, it would be worth having the capacity of the battery checked as it may have dropped from lack of use.
Lead sulphate begins to form at 12.4v and its these sulphites that strangle the battery.