Another Dichotomy twixt UK and USA ! We (in UK) have a lot of Festivals , but NOT many 'camps' . UK festivals have a lot of Workshops where Vocal , Instrumental or Dance skills can be taught/learnt , but these are ancilliary to seeing a variety of good singers / musicians perform .
I dont know of any 'camps' as such other than places like Halsway Manor that 'do' weekends of instruction .