could the cause of our condensation problems also be that the previous owners got the cavity walls insulated and also related to the amount of insulation in the roof?
No, you are the cause of the condensation, and the way you use the property
The damp air is merely condensing on the coldest surface available. Change the frames for something else and the air will still condense on the next coldest surface if the conditions are right - which tends to be window reveals and wall corners