Dont leave your keys in the door firstly!!!

Instead of using thumb tacs, I would have used razor blades!! much more effective or if you really want to shit em up hyperdermic needles!!!!

Anti-climb paint on the wall, the needles on the top, if they complain to the council or police just say that it must the the junkies who hang around doing it!!

get some motion sensor flood lights for the garden and maybe one for the front step, some cctv maybe. or how about an alarm system with monitering??

booby trap your garden with atrip wire and firectly behind it.... a pile of broken glass!

get a dog or two, they will be a good deterent, or you could try and report the chavs to the council for different things try and get them moved?

me personally, I would go rount there with a coule of mates, kick the front door in, smash fuck out of them, a proper demolition job!! with the promise that you will be back to finish the job next time they even walk past your house!!!!

what ever you decide to do, do feel bad they deserve whatever they get!!!!!