Just an update for anyone who might look at this thread for answers which are not easy to find.
I did the two days work at the end of February, mistakenly thinking from what I'd read that it could be averaged out somehow. That took me over the limit.
I think I did another full day and two half days over the next two weeks which was within the limit and I let them know. However they froze my carers allowance and I have not had any for more than two months.
My daughter then went back into crisis and I have been unable to leave her to work for 6 weeks anyway.
I rang a few weeks ago and I had to post -POST!- a payslip showing I was within the limit but I still did not get any payment.
I rang yesterday and he said that someone should have done something or other which had not been done and I probably could now be logged as an irregular earner as I requested when it had all gone wrong. He said he would send an urgent email and I should be paid arrears and receive forms to be an irregular earner. This guy was better and was able to speak to me normally rather than from some script. Not sure how long to leave it before ringing again though since what they say will happen, never does.
My takeaway is that yes you can have earnings averaged out but this needs to be agreed first. Think carefully about letting them know as their first response is to cut off your payments and it's hard to get them back even if you know you won't have gone over across the month. Don't think they are getting on with sorting it out while you wait - nothing is happening - it seems you have to keep calling.
It's crap. It would be better for me - better for my daughter's independence - if I could pick up a bit of work but I'm not sure it's worth the financial difficulties we've had to face.
I'd like to think that we are working towards my being able to work again and my daughter to be well enough for this to happen in which case I won't need the benefit but the administration around it inhibits our attempts to take these tentative first steps.