This is the front of the house and I need to keep the window and the panel. Inside the house we have radiators attached to the inside of the panel so removing the whole thing would mean relocating that which isn’t something I want (or afford) to do as it would need pulling up significant areas...
As shown in the picture, my property has number of these large window and panel combos. I am guess from the 1980s, they are 3m x 2.5m and all one unit! The insulation and double glazing is poor and the rooms are usually very cold in winter. I could replace the glass with something better but...