Got a 52 Reg Zafira and recently one horn button has failed to work intermittently.
It will only work when the steering wheel is turned slightly to one side so I guess it is a wiring loom issue?

My query is, how much of a job is it to replace without risking the air bag going off.

The MOT is due in July and a new loom looks to cost around £15. The Zafira is well worth repairing as it has only done 28,000 miles in 18 years.