Hi Denise,
The acrylic "glass" used for caravan windows is resistant to most things except it can be damaged by aggressive chemical solvents - like nail varnish remover, and it is very easily scratched - it is not much harder than your finger nails.
So to clean acrylic windows, a household cleaner like Flash diluted in a bucket of water is perfect and apply with a new, soft cotton cloth.
Household window cleaner - in a spray bottle - is OK for that final polish.
Don't use washing up liquid, it's loaded with salt to make it thick and gloppy.
Don't use an old cloth - it may have bits in it that will scratch the window.
Robert