Child of the 80's, teen of the 90's here too.
Due to my DB's severe disabilities, my DM couldn't work. DF worked at least 50 hours a week in a v low paid job to make ends meet, so for most of the holidays it was just me, DM and DB.
Because of the difficulties associated with going out and the lack of money, we had to make our own entertainment.
We'd go to the library once a week and do the weekly food shop another day.
Me and DM used to play board games and card games, play in the garden if it was nice. I had a computer in the 90's, so I used to get a bit of screen time, or I'd watch some TV, though I don't remember what. I remember it was all a bit boring as there was obviously only 4 channels.
I'd help DM cook dinner or we'd make cakes.
I used to spend a few days to a week staying at each set of Grandparents and we'd have a few days out with my Nan too.
I do remember being quite bored a lot of the time, but I also look back on it nostalgically.
I realise now that my DM probably thoroughly enjoyed the holidays as she had me and DB around. When we went back to school she had the same weeks - i.e. a weekly library trip and a weekly shopping trip, but no-one to talk to or play games with during the day. No wonder she devoured books, knitted a lot and had an immaculate garden!