We have a spare window which is free to the first person to come and collect it. It will need new framing timber adding to suit the depth of your wall cavity. The current timber has had its previous fixings dug out of it using chisels. (Could be filled if it’s not in a prime spot perhaps (maybe suit a garage etc).
Dimensions of the frame itself (inner – would fit into a hole of this size) are 1800mm x 1000mm.