Thanks @Furries! We have had a much better day today - not a single pee or poo inside, all performed outside owing to my stupendous psychic powers (and watching Kikopups videos). Have also managed to tone down the biting a little, taught him a solid sit, and a version of "leave it" (I have accidentally reinforced him looking behind him rather than actually leaving something, but I'll take that).
He's got a vet check tonight, which is just as well, because I've noticed he has a spotty rash on his tummy and is itchy: he had some discharge from his nose and eyes; and he's got terrible smelly wind, which is unusual in one so young. He also chases his tail a lot and I've noticed there is a weird lump on it. 
Anyway, puppy pic for everyone. I've had no news on at all today, no TV, no radio, haven't opened any SM or news app. Just been on puppy duty. Although DH has come home saying he's got a sore throat and a headache...