My main advice would be NOT to go with Vita Cannon Park. It is overpriced and low quality and preys on first year students who didn't get their first choice in on-campus accommodation.
All first years are guaranteed on-campus accommodation and I would really advise to take this. First year at university is about learning about life and making friends and living in a studio apartment is very isolating and doesn't allow the full university experience.
There are some very nice and very expensive on-campus accommodations if you value luxury and an ensuite, such as Bluebell and Cryfield Apartments/Townhouses. In my opinion, the higher the price, the less social the atmosphere. Most of these have 3/4 double beds which are larger than most. If your son is very very tall, I'm sure warwick residences could offer some other options if you need a longer bed.
If your son values privacy, I would avoid Rootes like the plague. It is very much the social, party residence.
Overall, all student accommodations will have shared washing machines and kitchen and it's honestly not as bad as one may think. It teaches life skills and social skills and how to live and work with other people. I find that people who have lived in a shared bathroom/kitchen residence are much more mature after their first year and I wouldn't want your son to be lonely and miss out. It's actually great fun and a really safe environment and is part of the experience of university.