In the house or out? Do you have a garden? B&m bargains always have shitloads of cheap craft make your own jewellery/sock puppet/cuddly toy things, that would maybe be a nice thing to all do together if they're that way inclined, put some tunes on, eat some pizza, sorted.
Egg and spoon race, sack race, three legged race? Medals Treasure hunt in a quiet corner of a park? Fairy hunt and fairy picnic in a wood? Hide some fairy clues in tiny writing and mini things the fairies have dropped, have a picnic tea with mini food items set out for the fairies that you can leave there?
Not sure how to keep costs down if raining, you could still do treasure or fairy hunt in weliies and raincoats, and then have a back up cafe or tea room to take them too afterwards?