The start is worse than the ongoing, to be fair.
Form F takes quite a bit out of you, it's very personal and digs deep into your private life. Some of the personal stuff you've shared here with us will be explored in depth.
The initial training is quite a lot squeezed into a short space of time.
But, once the form F is done, you don't need to return to it. The training becomes a refresher course every three years. The contact invariably drops, as parents become unreliable, or face up to the reality of their situation.
It gets better. If possible, consider making space for another bedroom, convert any big enough room and take an extra child. The income will help. Use any available ways to claim extra money - DLA if the child has any disabilities. Claim your mileage back. Speak to your SSW, ours will pay you back for one activity per week as long as you pay for one. Our boys do football and tae kwon do. You could do swimming, dance classes, rugby, Scouts - it gives them routines burns energy, and gives you a topic to write about in the interminable reports we're expected to write.
Other than that, just keep going. Watch yourself and cover your back. The worst thing you can have happen is an allegation. You won't be told any details, and you can be put through hell.
It's brutal at times. Would I recommend it? Honestly, no, not at the minute. But I'm not in a great place myself, but I'll keep going and things will pick up.
I think you're in the toughest position right now, and in a few months you'll find it a lot easier.