Right, my horn has not been working for some time now, I've tried replacing the Horn with my dads two tone Jaguar Horn... but nothing .. I do remember when it first start not to work it used to be intermitant where it worked sometimes and sometimes not... does this mean its the horn that isn't working and not the circuit?

And I tried to check the fuse.. but its one of those block ones..dunno how to check them..

You'll need a multimeter before you start searching. Both the continuity tester and voltage features will be useful in tracing the fault.

Swap the fuse for one you know is ok and try a horn you KNOW is not faulty. If it hoots you know the circuit is ok. The problem is likely to be the wiring connectors at the horn. Look closely for green goo in the crimps