Got one! What a pain in the *** though.
Managed to get a chat window going, and made it through to someone after 20+ minutes waiting, sadly, they could only offer the deals I could get via the website - the best there was Pixel 6 for £369 with a max of £259 upfront, then the cheapest 12 month contract was £23, or £30 with their 'Entertainment' deals (had Spotify via this last time). I tried the old "but the reptations team have previously offered better deals", but after they said they would try - I got disconnected and booted back into the queue at number 153!!
I decided to just go ahead and buy via the website - some posts on HUKD suggest that if you do it this way, you can call and pay off the outstanding balance of the phone, and also cancel the airtime contract, providing you haven't activated it... might do that, then see if I can simply extend my current SIM only deal, or just go elsewhere for that.
I better trawl this thread and look at cases etc, and probably have to order a dampener to fit on my motorcycle mount, as I suspect the Pixel might get damaged otherwise!