You should be able to port, in theory.
My suggestion would be to raise the question on a more specialist forum/site sch as ISP review forums https://www.ispreview.co.uk/talk/ and Kitz https://forum.kitz.co.uk/
One other thing..
I too have had a contract renewal email from Now, saying "Based on wat you have" a 12 month deal for over £30 a month followed by a lot of text , and then underneath more text, followed by a price of £21 month on a rolling 30 day deal, with a discount period expiring 12 months later.
So a renewal "deal" for 12 months that is more than i have been paying, or stay were i am on a rolling contract and pay the same price for another year