Events/tickets/courses:
School of Artisan Food
Kielder Observatory
Ministery of Upholstery
Huntlands Farm upholstery
Been to stuff at all of them and had a great time. Not cheap for sure. Less specifically and probably cheaper, local places doing craft courses (one near me does christmas wreaths, dried flower wreaths, terrariums, etc), cookery courses, baking courses, wine making, preserves, cheese making, blacksmithing, jewellery, pottery, lino print. The list is endless. Experiences on heritage railways, goodwood etc. Comedy tickets. Films with live orchestras. Paddle boarding/kayaking/wild swimming day.
I know this is probably not what you were thinking but it might spark some ideas for someone!
I've bought pyjamas from Their Nibs for others and been impressed.
Sous Chef has interesting foodie bits
Refound Objects has some gorgeous bits and bobs, some old and some new
I will keep thinking but obviously ebay/etsy/vinted/facebook/gumtree for second hand stuff too - books, clothes, vinyl, cds, kitchenware, blankets etc