@ISaySteadyOn I'm really glad it was helpful. Have posted below. I'm not an expert, just someone with a bit of experience being home educated (and a bit of experience helping/tutoring home educated children.)
Overall, I had a really good experience, and I'm that fairly rare thing, someone who was home educated all the way from pre-school to sixth form. I'm very pro home education, when parents choose to do it. (Very much not pro parents being forced into it!) Here's some thoughts, take anything that helps and leave the rest.
I have a brother close to my own age and we did a lot of stuff together - if you have 3 under 11 I would definitely do as much as possible with all 3 of them together rather than trying to do different things with each. This may actually pull the younger ones along quicker than school would as they want to do what older siblings are doing. That was definitely the case in my family. So you could get them all doing the same thing (e.g., writing a daily diary entry) where obviously you'd expect a bit more from an older child but everyone has the same task. Or you could all do a basic science experiment together and then one child draws a diagram of the equipment, one writes up how to perform the experiment, and one writes up results.
My parents actually favoured a fairly formal education - we had a timetable, mum was very hot on grammar and spelling, and indeed I learnt Latin! I suspect that wouldn't really be an appropriate way to proceed when educating as an emergency during school closures though. I'd recommend a basic routine though - starting, finishing and having breaks at the same time each day. On the subject of routine, you should be able to make your "school day" shorter than an actual school day because schools have a certain amount of unavoidable wasted time. At primary level, we worked 8:30 to 10:00 and 10:30 to 13:00, with maybe a nature walk or some craft or gardening or something in the afternoon, or maybe a completely free afternoon. Certainly no sit down reading/writing style work in the afternoons (unless, very rarely, we'd been misbehaving horrors in the morning, played up and not got the work done when we could have - this also motivated us not to play up too much in the mornings.)
Mild bribery is absolutely a fine technique. (I don't remember this but apparently I learnt the alphabet by being given a raisin when I could match a letter to a sound!) I'm pretty sure at one point my parents bought stickers for reward charts wholesale. This is ideal for when you need one child to get on with something so you can give attention to a different child - offer a reward/sticker to the first child if they quietly get on with the work.
A bit of inter-child competition can also work, but obviously you know your children better than me - if that's likely to lead to one child always "winning" and being unbearable about it, for instance, then no. As an example of what I mean, my brother and I had our own age/stage appropriate mental maths workbooks. We'd compete over who could (correctly) answer more questions in 10 mins.
Something that's definitely worth doing is reading aloud. Our mornings used to end with this, and it's a great memory I have - I'm already looking at books and imagining how much fun it will be to read them to DD. I wouldn't worry too much about them being great literature - I'd pick a book you like (which is age appropriate) as they'll probably enjoy it if you're enjoying it. They could colour or play with something quiet (Lego doesn't work!) while you read.
Oh, and if you want to do baking - you can extend that to cover maths and literacy if you like. Give them ingredients in lb and oz and scales in kg, and a conversion graph and that's some maths, and get them to write up the recipe afterwards, and that's literacy!
Khan academy has excellent maths resources that a 10 year old at least could probably work through by themselves - they have video explainers on a topic and then self-test questions. It's a free site.
That was very long, I hope there's some stuff in there that might help (and that it's not all just ideas you've thought of already).