Thailand
This is exactly the sort of thing I like bringing back from Thailand: small enough to fit in a bag, but specific enough to remind you where you bought it. I would buy a couple of packets: one to open while travelling and one to bring home unopened, because snacks have a habit of disappearing before the flight. It is also the kind of thing you can talk about when someone asks what you brought back, because there is usually a little story attached to where you found it.
Thailand
I would put Thai curry paste on the list for Thailand because it is the kind of thing that feels useful once you are home, not just another airport purchase. The best version is usually the sealed jar, tin or packet from a normal supermarket, spice stall or food hall, not the most expensive tourist version. The reason it works is that it gives you a quick reminder of the trip without needing to keep a fragile ornament safe forever.
Thailand
When I think of an easy, crowd-pleasing thing to bring back from Thailand, Thai silk scarf is a good pick because it does not need much explanation when you hand it over. I would avoid the obvious tourist print and look for something with a local pattern, fabric or cut that still works with normal clothes back in the UK. I would rate it higher when it is locally made, clearly labelled and easy to use at home, and lower when it is just tourist packaging.
Thailand
Nam prik chilli jam is worth adding because it feels like something you actually noticed while travelling through Thailand, rather than a generic souvenir. The best version is usually the sealed jar, tin or packet from a normal supermarket, spice stall or food hall, not the most expensive tourist version. The ideal version is modestly priced, not too bulky, and good enough that you would buy it again even without the holiday memory.