Check out the prospectuses of your nearest colleges of further education. I think most such courses come in around £500 each. Certainly that's the cheapest here in Rotherham, but others have indicated that some colleges can beat that by a significant margin.
I'm saddened, but not surprised, that most colleges have spurned the community to concentrate on courses with qualifications at the end of them. Although they may argue that it helps people get jobs I would rather believe that it's the profits that motivate them to no longer support any 'introduction to' courses for the DIYer/hobbyist.