I’ve not actually used a Roccbox but I did a bit of research and decided the Ooni looked better for decent, consistent results (especially the Koda as gas is incredibly consistent) - turn it on, leave it for 15 minutes and its perfect.
Re: Dough - I don’t know if you can get in the UK, but a few places here do it. If you are looking to make Neapolitan style pizza, I would make your own dough. The stuff I have bought previously from stores here to use in my regular kitchen oven is made with regular flour as opposed to ‘00’. Regular flour doesn’t do well for a very hot, quick cook (60-90 secs in Ooni) so I would recommend you make your own dough with 00. It’s a piece of piss and you basically do it 24 hours ahead, or failing that the night before/morning of the day you want to have it and leave it out to prove. If you are going to the trouble of buying a pizza oven it’s worth making the dough, using San Marzano tomatoes etc - really makes a difference.