I have very active children. No sedate colouring for us! They are 10 and 13 now but a decade ago he was entertained by the park and anything outdoors. I did do a couple of church groups on my non work days to get me out the house and talk to other mums. I'm in a city and the provision is very good. It wasn't a posh area and they usually had a great selection of toys for preschool ages 0-4, an activity like crafting or messy play laid out, and a good selection of snacks.
I swim and it seems most people take their dc to baby splash which is not an expensive activity. Sounds like that might be a no no for you if you live rurally.
We could spend all day in the Park, good weather and bad. We still go now as no one in my family likes sitting around at home. Jumping in puddles and picking up sticks, building dens, playing games together acting out stories or scenarios like being a shopkeeper.
We'd also go to the library, get a book and read it there. I didn't go to rhyme time past aged1. Young dc are usually just curious and happy to be out getting into stuff. A trip to the supermarket is exciting (but miserable for mum and will involve buying food they like) (I avoided shopping with them).
I'd draw the line at paid for food and drink on normal days out. Ice cream is for weekends and holidays.
As for food costs its really not as expensive feeding toddlers as adults but they are an extra mouth to feed.
It sounds like you're feeling the pinch and have too much time with them. All credit to you for doing SAHM this long. It sounds like your dc would thrive at nursery whilst you work, get a bit of yourself back and make some ££ too to spend on the DC.
If you think they are expensive now you've got a shock to come. Paid for activities get more pricey, days out are extortionate, food costs are MORE than you'd pay for yourself multiplied by number of family members as they tend to eat more than you and want more snacks. Clothes are very expensive for teens especially but it kicks in young with them wanting Nike trainers or expensive football kit. Today my dc asked him to get more "hair powder" which turns out cost £17 for 7g. I did not buy it! Their social life starts to cost you ££.
I pay for piano x2, violin x1, swimming x1, water polo x1, tutor for the youngest doing 11+, Fencing x1, football subs x1, scouts/cubs x2 plus days out and socials with all these groups and the kits and consumables and exams and competitions that these activities entail. We are a normal family, not wealthy.