I understand your panic, mouses.
Your youngest is currently eligible for up to 15 hours free nursery care which you can spread out over the week or some nurseries will do over two or three days.
You could use that time to volunteer in the areas you mentioned above.
If your first love was dancing, how about emailing your local dance school to see of they need any help, even if it's just supervising?
I have just started volunteering in a charity shop and as someone who is incredibly shy, I can assuredly say that it's so different forThe usual work environment. There is no office politics, no colleagues judging you on what you wear, where you're from, what you do. It's a mix of volunteers from lone parents, retired, and some with mental health or disability issues, amd I have found myself so at home in this environment, that I immediately felt useful and valued from day one. That gave me instant confidence.
I am currently looking to return to work after 6 years at home as a lone parent and from what I keep reading, yes it will be a struggle coping with school holidays, sickness, etc. but ultimately it will just mean that you will suffer financially and have to deal with it, because there is no alternative.
Everyone in our situation somehow manages it, so we must too. I am guilty of overthinking the whole process and have analysed the pros, cons, income, outgo, benefits entitled to, all the government help websites, paremt forums, Jobcentre lone parent advisor help, and worst case scenarios down to a fine point believe me, yet still haven't come up with any solution to avoid it.
It isn't avoidable. Going back to work will be a struggle, but it must be manageable, because so many others do it. That's what I've finally learnt. It's going to be jumping in at the deep end. I probably won't even know in advance if I can pay my rent or buy food shopping for the first month I'm in work. But I'll prepare for that somehow by trying to save a contingency fund beforehand, or if I can't afford that, well, ultimately, the rent will just be late won't it, and the kids and I will live on pasta for a few weeks.
I'd enjoy your last few months with your child before she starts school.
Things become clearer once you're on your own in the house for 6 hours a day.
You'll get your housework done in an hour then be gagging at the bit for some mental stimulation, so looking for work or voluntary will suddenly become an exciting not daunting prospect.
If you are claiming benefits, you are still entitled to Income Support until your child turns 5, so there's no rush financially, but I'd use that time to try and keep out of falling into a rut. Don't have daytime tele on even as background! And stay off the internet. She says, on the web in the middle of the afternoon 
Well, I do have a job website open.. Alongside Mumsnet 
On a last note, I'm learning to drive soon. I'm noticing that part time jobs are like gold dust especially one's that fit around school hours. I'm noticing that care work offers those hours. Poor pay, but convenient hours. It's most likely where I'll end up working.
Good luck, mouses, and chin up 
.