Hi Gavin
Had the same issue but I just bought a new (second hand) window off ebay for £30 and fitted it myself. It really is a doddle to swap out a window. Door cards and trim come off fairly str8 forwardly and then you just hoover out the glass and slide the new pane down and slot it onto the wind/electric mechanism. Bound to be a guide on here for at least getting the cards off and getting the new glass in is very easy.
I'm afraid I don't know what the score is with insurance though, my guess would be they wouldn't pay out but then again it's not like you were driving the car when the damage happened so roadworthyness doesn't come into it and you've not hit someone else. It might be they would stipulate you either need a valid mot or sorn for the insurance to stand tho. Best to give them a ring but perhaps try to avoid disclosing who you are, just ask for the details of whether your type of cover would be valid without an MOT given vandalism.
