You could just get the £23 plan here
and return it within 14 days! That would settle the Three question.
Alternatively either of the other two data allowance packages. The main difference being the unlimited data if you decided to keep it.
My broadband basic info/help site - www.robertos.me.uk.
Domains, sites and mail hosting - Tsohost
Connections: OnePlus 8 Pro max 165Mbps down, 24Mbps up on Three, and B311 4G, tbb tests normally 35-45Mpbs down, 65Mbps off-peak, 9-24 up.
To argue with mindless bigots is foolish.