Update 
firstly, Notanumber thank you for the offer but id already ordered one from MGFNMGTFBITZ.

it arrived and I've fitted it. In the process I've found i can bend like a contortionist, ouch! 

When i plug in the horns and blip the alarm it doesn't go off any more result!

..... however still no horn off the steering wheel button still. Ive checked the coupler and i don't think I'm getting continuity through it. So I'll order one. 

in the process I've snapped off a tab from the tiny horn button mounted in the steering wheel which is a swine.

This little car is really testing me!!
I'm starting to think this car has had a life of issues as many bolt heads and screw heads are mashed up. Dodgy twisted wires etc. It's only been owned by my god parents who would not of touched a spanner, it makes me think a rough garage has done this.