Thanks all for your comments, very useful and interesting!
House n1 and n2 do have a small bathroom downstairs though. Not ideal but the main bathroom accessible via bedroom isn't the only option, DD (once much older) and potential guests can use the one downstairs if needed, although appreciate a bit more difficult for DD as she'd have to go downstairs.
We are used to living in a 2 bed flat, I have personally lived in a flat all my life being from outside of the UK so 80sqm ish for a family of 3 doesn't seem that small to me, especially as he'd also have a garden.
I want to get somewhere we like but also don't want to overstretch for some of the reasons mentioned above.
Guildford is not the only place I'd consider but definitely the furthest away from London we'd go as we both commute and need frequent trains. I also don't drive so need to be close to the station and ideally town.