'Special interest' holidays tend not to be cheap. This website (with beginners guitar courses in Tuscany) hasn't been updated for 3 years(!), so they might not be running the courses any longer but it might be worth sending them an e-mail:
http://www.musikurlaub.com/music-holidays/
How about Irish fiddle playing?
See here:
http://www.kerryfiddles.com/
or here:
http://www.fiddlersretreat.com/
A course in the USA might be beyond your budget, but this place offers beginners courses with several musical instruments (including guitar):
http://www.folkschool.org/index.php?section=su bjects&subject_id=3
Chris