To think there MUST be a way to top up my income

Crime

What about an Etsy shop selling your handmade wares throughout the year?

The world never ceases to mystify me.

Off to Google 'teacher shoes'.

Could you child mind in the holidays only?

OF! Lol, there's a market for EVERYTHING!

There's loads of apps to enable you to get into the gig economy.

My DD is doing cat sitting, it's not well paid but she likes doing it. She's on the Cat In a Flat site (other sites exist).

I rent out a car parking space I don't use. Again, not well paid but better than nothing. Just Park or Your Parking Space are two sites to look at.

You could contact event organisers and set up to do craft services e.g. weddings, special birthdays etc. Easy to create things at a time of your choosing. I've no idea how much it gets paid though.

I didn't mean that you do the printing on demand! I meant that they get an instant pdf that they can get printed themselves. You just design a template. You could customise so they get their own version. E.g. custom stationery, 'Mr & Mrs [name]' etc. Though for a truly passive income you don't want to customise too much.

Red Bubble - upload your designs and they'll print on t-shirts, mugs etc. It means you can work worldwide with no trips to the post office.
Great that you've done wall prints before - so hopefully you still have the good reviews on e.g. Etsy? Wall prints are usually a present so naturally given at Christmas, you need to think year-round. Think of pop culture, memes, back to school, royal events, Valentines, Mother's Day, Father's Day, niche interests etc. Have a browse of bestsellers.

I'm actually a cat sitter hence my suggestion of it. Clearly services may vary - Most of my clients only want 1 visit a day, and I spend a similar amount of time in total - 35-40 minutes (sometimes a bit longer if a cat is very cute). Quite a lot of them have food on timers though.

What about freelance jobs in the content making field? Look up "Video/Photo editor for hire" posts online if you're good with editing programs. If you don't have those skills but you like the idea, start from getting familiar with various software like professional slideshow makers, programs for photo editing, video editing apps, etc. It'll take some time and practice, but once you're there (or if you already have some skills) you can post your own ads on Facebook or Reddit. Some people work consistently with photographers and videographers as their assistants for editing, so that could be a good way as well. You'll certainly be able to do this with your kids around, but make sure you can concentrate properly.

I’m a lecturer and have two side hustles. Might either of these be any use?

My subject helps here as I teach mainly digital marketing (as well as more traditional advertising, PR etc) - I manage social media for a local business. I actually love doing it, and it “keeps my hand in” in terms of doing what I teach.

The other thing is writing and credit rating for our qualifications body. This is more ad-hoc but pays very well. I have a contract coming to refresh a module which will pay £500 pre-tax. It goes in bursts - last summer I think I did two modules, but the summer before was four, a couple of which were double credits (so twice the fee). I also “vet” for other writers - basically checking it meets standards - which pays a lot less but is usually easy money. Credit rating is making sure modules are at the right level for the student group/award and is time consuming but tends to pay very well, especially if the modules are for training providers. It’s often over summer but not always.

Much, much more ad-hoc, but I am on the reader panel for Hearst Magazines and do lots of market research stuff. Again, it’s relevant for my subject, and I find it interesting. A focus group or week long study can pay £100ish (but is usually eg Amazon vouchers rather than money) and is easy to do. I often get sent products to try before they go on sale and can be one of the “74% of women said…” you see on ads.

Where can you sell feet photos? I have pretty feet (the only part that is!) and I'd like to do this!

I know you've ruled out mystery shopping, but I would consider giving it a go. The fees aren't as good as they used to be, but you can still make a bit of money. You do need to sign up to every mystery shopping company you can find and then check their job boards regularly. The trick is to try and find assignments geographically close together so that you can do them all easily without too much travel.

My daughter does this , she started helping friends in the school holidays and now does it at weekends as she works now.

You need a debt repayment plan, however it happened

How about metal detecting at the beach

Yeah but that’s boring 🥱

If OP wants less R rated methods she could also start a book reading club and charge for entry

You need to sell your knickers on a site called
” all things worn “

you would be amazed at the stuff men will by
buy a pack of 10 pants from primark where them and flog em
tights especially American Tan ones 😆 if you send a photo of you wearing them with them are popular

webcam/ phone chat is another way of making fairly decent money if your broad minded

can you do magic tricks for kids parties maybe? or be a clown

@Unexpectedlysinglemum no one should be keeping rabbits in a portable hutch - they need lots of space to stretch and run.

Hamsters, gerbils, okay.

I would love to find someone who offered local “bunny minding” services - basically someone to come into my garden twice per day when I’m on vacation and feed the bunnies, sweep them out and change their water. I’d pay £12 a day for that (it would be about 30mins effort per day).

have you considered adult bike riding lessons for people at the local park?

Small pets holiday care eg rabbits etc come to your garden in their hutch.

Babysitting.