I bought my property 23 years ago and 21 years ago we had a grant for new roof and windows and had a velux window installed in the attic roof, strengthened the floor and put in floor boards with a pull down stairs, we have just replaced old for new and put in a new fixed stair case due to the existing not being fit for purpose, re plastered and insulated the roof, added a few extra plugs, a radiator because of the damp and painted and decorated.
I have now had a letter from the council advising I have not made an application to building regs and have 28 days to reply.

Ultimately we want to use the loft as a study/walk in wardrobe. Do study/walk in wardrobe rooms count as habitable rooms in which case we would need to re-do the loft conversion entirely with up-to-date building regs? Or can we get away with doing the above refurbishment without building regs?