Dismantling the boot lock is really easy if you know what to look for. So hopefully this will show you clearly what to do.
In my case my lock had stopped locking no matter now I turned the key so i'll tell you how I fixed it (and therefore save me the cost of a new lock and an extra key on my keyring!)
First of all take the lock off the boot of the car. There are three 10mm bolts that hold it in place.
The lock is held together by a small C shaped circlip in one of the slots. You can just see it here in the longer of the two slots
You will need to push the lock in 2 or 3mm to get at it (It helps to use an old tooth brush to clean away any dirt). Grab it with a pair of pliers and pull it out.
From here you can remove the lock barrel, it should just slide out (pulling it out with the key can make it easier).
Once the lock barrel is out, slide out the metal locking piece, it should just fall out but it might be stiff with muck and dirt.
With the metal removed, the lock barrel housing, and the spring should come out easily. These are all the parts you should be faced with.
Use plenty of WD40, a tooth brush, and a scrape from a screw driver, to clean up the lock. Stick the key in and out the barrel and make sure all the lock pins are moving freely. Once you are happy it's all clean reassembly is just a reversal of disassembly. Use plenty of lube to make sure the lock moves smoothly and if you have it use locksmiths dry graphite lube (it's made from graphite dust so dirt doesn't stick to it like oil)
And that's it your lock should be running smoothly!
If your lock wasn't locking/unlocking, it can be fixed, and saves getting a new lock and a new key. Turn the page!
Dismantling the lock 
