We chaps it all seems too much trouble, I can't afford to mess it up, the van is only a couple of years old but thanks for your input.

I have polished loads of caravan windows bike screens and car headlights . In most cases on caravan units i have used my electric da and a polishing compound all over . I then polish the whole window with a uv based polish .If there are deeper scratches I tend to remove with say 1500 then 2000 then 3000 trizac disc paper followed by the above mentioned process . The big no no is dont get too much heat into anyone area ,keep the da moving and spray often with water to the surface .