DD went to afterschool cooking classes at her primary school for a few years, we paid £6 for an hour each week (think about 15 children at a time). As lots of things take more than an hour due to cooking time, often what happened was that the woman running it made a batch up to a certain point, then the kids took that and completed it, put it in the oven then they started a new batch. Meant they got to practise the whole thing, didn't have much hanging around time but also get a completed one to take home. So eg they made bread so started with some already proved dough, kneaded etc, shaped, put in oven, then they started making dough from scratch. At the end, they had the cooked one and the "half made" one they could take home and finish if wanted.
The same woman ran holiday courses in the local church hall and ran smaller courses from home. DD later went on a teenager/DofE course at her home where they did 2 hours for £15 each, with I think 5-6 teenagers. She also ran children's cooking parties (mostly pizza/baking), adult cooking parties (often making chocs etc) and "learn to cook before you go to uni" courses.
I do think the costs of getting started (eg having six of every piece of equipment, first aid course, hygiene certificate, etc) would only be justifiable if you intended to do more than 1-2 courses a week.
If DD hadn't done the one at school, not sure I'd have been happy her going to the home of a stranger. So you might want to think about getting your name out there by running one in a school first. On other hand, as you are a TA then you may have a ready crowd of people who already know and trust you so not an issue.
By the way, DBS can be transferable - most organisations won't accept a DBS from another organisation but they can do so would have thought you might be OK on that front - but obviously do check!