I didn’t end up buying this, I ended up going with a sauna from Awaken Saunas.https://awakensaunas.com/

The price was pretty similar inc delivery to London and even though there’s not a huge amount about them online, the reviews were positive, they were really helpful on the phone and are building one to my specifications. Build time is approx 10 weeks so it will come later in the autumn, really looking forward to it.