First a pack liner when carrying it is not a bad start

Second in a tent condensation can be a problem with certain tents. Generally the smaller the tent the greater the issue. Tents that do not have a top vent and lower ventilation are going to be a problem and does make me wonder the thinking process behind some designs. Also in a small tent it is easier to bump the sides and get the bag damp. Depending on the bag this is more a annoyance than a serious issue as many modern bags have a water resistant coating. The issue is a wet bag losses warmth rating and is just plain unpleasant.
The best cure of condensation is to get a tent big enough for the people in it not to touch the sides and has a design with flow through ventilation and then have the tent open as possible. It might be a problem for some people that the Microlight is just too small for many people.
Julafreak what bag (brand, weight, length, rating) did you get and the cost?
Cheers Brett
"lt only took six years. From now on, l´ll write two letters a week instead of one."
(Shawshank Redemption)