Thanks all for your replies! I'll try and respond as best I can.
I'm not going to post a link because I've already shown a couple of people and although it's probably already a bit outing anyway, I don't want to be very outing!
The dimensions are as follows according to Rightmove (no floor plan):
Kitchen 7'7" x 9'10"
Living room 10'10" X 10' 8"
There's also a small conservatory on the back of the kitchen which could fit dining table.
Bedroom is 11'11" x 10' 10" and an extra toilet and dressing area.
There is also a loft hatch to fully boarded out loft with skylight.
The sellers say their intention was to add a loft conversion but they haven't got round to it. We have every intention of properly looking into planning permission/costs etc .. before going ahead but we've been for a thorough look around and it looks possible.
I know it sounds a bit hard to believe but DH actually makes bespoke staircases in his business! He made ours at home and has made a few very clever ones where space is limited although tbh the landing is spacious enough.
The loft probably couldn't include a toilet as well but there is a family bathroom and a en suite so it wouldn't be too problematic.
The house is still £130k so it's not ridiculously cheap. The area its in is expensive hence why we are considering (and only considering right now) this option.
Children are 6&8.