My dc are teens (13/14) were not skint, but we need a new roof, so have no budget for holidays (camping isn't cheap, at least not in our area, cheapest deal I could find per pitch was £25.00 per night), then add in the fuel costs you're suddenly looking at £100 for three nights away!
My dc have limited screen time (max 2 hrs a day). The weather has been crap, so walking to the skate park and doing some wheels, hasn't happened yet, although as soon as we get break in the weather, they'll grab their wheels and go. Dd is doing art for one of her GSCEs, so she's working on her big assignment, and will have to work on it over the summer holidays too, as she's doing something incredibly complex and intricate. She also has to do maths practice (she's shite at maths), so she does 40 mins everyday, otherwise I don't think she'll pass her GSCE and she's going to need to, for the job she wants to do. She's also doing a guiding challenge; take one or two items of clothing and upcycle them, she's taken a a dress she had when she was 8, removed the bodice part from the shirt, and redesigning the skirt, she's cut stripes of fabric to add to the hem line to make it longer, and because it had a gathered wait in the original form, she's taken it in with a funky bright wide waistband. She also found a denim jacket in a charity shop for £2.00 so she's giving that a new lease of life by making an appliqué wolf (she loves wolves) which she'll then sew on to the back of the jacket. She's so far appliquéd a large moon, and the wolf will go on next!
Ds is teaching himself anime cartoon drawings, and making up comic strips. He found a couple of white t.shirts in a charity shop for 50p, and we have some fabric crayons (I got them years ago, when they were much younger, but never used them!) so he's going to 'anime' his t.shirts😂.
When I'm not working, we play board games/ card games and word games, Cluedo is one of the favourites, but also Chinese checkers, chess, and ludo, various card games and their 2 favourite word games are balderdash and Scatagories. Admittedly the games are all ancient, and I know buying new games isn't cheap, but card games are inexpensive.
When they were younger we used to do puzzles, and then use sticky back plastic over the puzzle once built, and then hang them on their bedroom walls, Dd still has a couple hanging up (a wild flower id puzzle, map of the world, and a cool 3d wolf one....which was really hard to build!)
We're also blitzing the house, so the kids are helping with that (dd just sold a load of her Sylvanian stuff on eBay, and ds a couple of Lego sets, so they were both chuffed to make some money).