Windows just fitted and had expected them to be almost tight to the side walls but there are gaps of up to 1.5" in places and no gaps in other places.
I am just wondering if this is normal or not before I go opening my mouth to window people!
Windows are not "fitted" until the reveals are cemented in. The reveal is the bit of concrete / plaster / render that closes the gap between the window frame and the walls, internally and externally. 1.5" sounds like a big gap; is it a little draughty in the house?
It would be standard practive to allow up to 20mm tolerance for fitting of new windows in a new build, that is to say the window could be up to 20mm narrower than the structural ope; measuring for replacement windows is a different matter. This tolerance must allowed as opes may be off square/ off plumb etc.