Just to follow up on this if anyone is interested…
6ft/32in waist and went for the medium.
As above fit is a bit weird, arm and leg length are good but slightly tight around the shoulders when seated on the bike, baggy around the waist. Would have liked the legs a bit more fitted but that’s a minor point, baggy waist with no adjustment also isn’t really an issue due to it being a 1 piece it’s not like they can fall down.
Tried it out, weather was a bit too warm and dry (would have been fine in trousers and a jersey) but was really impressed with it – will be saved for the wet uplifts/filthy weather/cold night rides but should make getting through the winter a whole lot more enjoyable. Would recommend despite if you can get over feeling like an enduro teletubbie.