This stuff isn't as easy as it looks, and I suggest you spend some time looking in to it before spending your money. I spent lots of time looking and eventually decided that it was too expensive to make one of these things. You'll need to include cost of a transmitter capable of switching the autopilot on/off and be capable of flying it manually.
The main problem is that the quadcopter is inherently unstable and needs constant corrections - which is where the gyros come in to play, but the hardware/software to do this is not trivial.
Google Quadcopter, and Tricopter.
A lot of people seem to be using Arduino variants. There are also some quadcopters that are pre-made, and also the control boards pre-made.
For insurance join the BMFA, http://www.bmfa.org/
, which will give you plenty of third party insurance for £31 for hobby flying.