Yep you are right but it was only affective from oct 2004 i think, so if you just say it has been there for years if anyone comes round and inspects it.
As for ways of doing it if you are taking it underground make sure you know where it is, theres nothing worse than your family doing a spot of gardening when you need the power most!
You can get cable in lots of places now, if you know what you are doing it might be worth taking some new cable from the fusebox and putting its own fuse in there, because of the weather conditions outside etc if it shorts out it will only take the fuse out rather than taking out all of what ever breaker you put it on... good luck, make sure you turn your power off before you add onto the circuits!!
Jono