Sorry the course was fully booked because it sounded really interesting and enjoyable. I suspect a lot of single people book them because you have a chance to meet new and interesting people in a pleasant and sociable environment.
Now it's the summer holidays, a lot of local authorities are organising play schemes for children and looking for volunteers to help run them. It may be a little late in the day to get involved, and you might find you need some police clearance to work with children, even in a volunteering capacity. Still, if kids aren't your scene, opt for clearing brambles or dredging ponds and rivers next year with individuals of your own age. I'm sure this involves lots of friendly evenings down the pub afterwards to clear your throat from all the dust of the day.