Right, I'm moving house on Monday into a house which currently has tenants in. They are leaving the day I get the keys, and as a precaution I want to change the lock on the front door and I'm just wondering if anyone on here can tell me if this is a diffficult thing to do?? It's a wooden front door with a normal key lock on there at the moment, and I can get a new lock from B&Q. So rather than pay a fortune for a locksmith, should I attempt this on my own??