That's a good one...
...'Another idea would be to get booked at say Whitby and Sidmouth festivals, which are each a week long and both run children's' workshops'...
....The idea of 'just getting booked' at festivals that, by this time, have likely allocated their budget and are well on with formulating their programme.
...the idea that 'just anybody' can ring up out of the blue and be given a place.
I remember Margaret Walters (of Australia's Walters & Warner) asking along these lines the other year, offering to sing for free at a festival - and told in no uncertain terms what to do with herself!
Good luck!
If you pull it off - do tell everyone else what the trick is - there's lots of artists that would love the opportunity.
They too have this fantasy - playing the main stage at Cambridge and Sidmouth and all.