UK seed producers (not the big boys)

Another amateur tomato grower/seed seller https://nrtomatoseed.com/

Is it you TMTT?

No! But I think I've seen that name around somewhere, probably when searching for tomato seeds. Not that I'd ever pay (or charge) £5 for a packet when the Latvian lady I ordered a lot of this year's varieties from only charges about £1.65.

Can you post a link to the Latvian lady, TMTT?

https://en.tomatoeden.net/

She has over 4500 varieties, so have fun browsing! Some of them, like the Jarsons, are quite experimental.