Does anybody know if it is possible to change the glass in a front fog? If so where can it be got?

The glass cannot be replaced. Your best bet is a replacement from
a breaker. Should cost around £50 and almost double that for a new
one from a dealer.

Or get one from someone who's converted to spots.

I've got a pair of MY02 fogs that have never been on the car. I bought the scoobie foglight kit for the brackets, switch, relays etc etc and used them to fit spots. Make me an offer.