It sounds like your house may not have been lived in for a while. We live in a newly renovated flat which had been empty for a few months before we moved in, and despite the new paint and fixings, we had some trouble with mold in the blinds and condensation on the windows. Invest in a good dehumidifier, run it steadily for a few days until the house has dried out, then run it intermittently whenever things start to feel a bit damp. That should keep the mold under control. Remember that mold is not dirt; clean houses can get it too. And above all, don't let this put you off living in the UK! Dampness is just one aspect of this country, there are lots and lots of good things too. It sounds like you've got a truly enviable situation, try to keep your eye on the positives whilst working out the negatives. A week is no time at all. I bet you'll find things you love about the UK really soon!