Oh Richard, what have you done?
The blue Himalayan poppies are a path to insanity!
For those of us not in Scotland, start with the bitter assumption that these plants want to die.
They are not reliably perennial even under optimal conditions, so you are looking at finding a regimen that keeps them alive AND gets flowers off them.
Most growth points die if they flower, so you are always looking to keep some growth points that don't flower.
Large containers, so they look slightly over potted, with ericaceous compost is traditional, but in my hands [I've killed lots of them] sharp drainage and never drying out seemed more important. Don't let them get hot.
Annual division and repotting into fresh compost kept them alive a bit longer.
Once you've killed all the named ones from
Edrom, either regain your sanity and enjoy them while on holiday in Scotland, or grow 'Lingholm' from seed as a bedded out biannual. From seed the genus has quite a few biannuals that stand a chance of getting to flower.
Keep us informed of how you do.
The only ones I know of in England, even if they look like 'permanent' plantings, are bedded out annually.
Chad