Hi Lisa, sonic, I wouldn't personally use any household cleaners for caravan windows as they are meant for glass not acrylic and contain all kinds of nasty chemicals, use one of the dedicated cleaners they are not hard to get hold of.
When you clean your windows hose them down first to get rid of as much crap as you can, whatever you do don't use a bucket and sponge as you are smearing them with all the grit that you have just washed off acting like sandpaper.Use the same method on the fly's graveyard on the front windows and keep hosing it until it softens.