That's a real shame about how badly publicised it is! I seem to recall that it was fairly well advertised where I am- but we are quite a deprived, small, rural area and nobody would have signed up had it not been pushed in our faces.
I'm pretty sure that youth groups were commissioned to run the scheme- do you have a Connexions where you are? Might be worth asking them. Facebook is always a good one to try- the scheme in my area was publicised through its own page and had full details of how to apply.
I had a look on google and I think your DC can register their interest here and they will get back re how to take part in your area!
Can confirm that it is not too good to be true!! 
Redkindof my girls didn't actually go together, they both went when they were 16 (they are two years apart). DD1 enjoyed it so much she went for two consecutive years and volunteered as a group leader on the third. If anyone has quite shy DC, encourage them to sign up with a few friends- as far as I know, they are willing to accommodate this. Both of my DDs went with a friend or two, but by the end, it didn't matter much as the whole group had become friends.
Honestly can't recommend it enough. Kept my girls occupied for free for three weeks of the holidays that otherwise would have been spent moping around bored. They both came back more confident and more aware of their own community- I saw a real change in them!