Season 12 is still available - albeit not in limited edition - here https://www.amazon.com/gp/product/B079PT1N7W/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1
I had a look for the Region 1 version but I can’t find it. At least it’s not currently on amazon
It's on Amazon.com for the equivalent of £35.
I would still recommend waiting a few more weeks to see if there's any re-release news, particularly since I'm not sure if a Region 1 blu-ray needs a specific kind of player to work in the UK, but if you don't really care about the packaging and you know your player will play the discs you may as well order this version.