Well, i now know what that fecking clicking was on my front discs. Clearly it was wave washers giving up and breaking (no pun intended!).
Many thanks to everyone's contributions. I have started with the cheapest option first (just replacing the wave washers and fitting stainless shims) and it has sorted everything. Brakes are now smooth, quiet and doing their job.
My next investment will be new brake lines. I would have done it this weekend but after a call to HEL Performance, they said they wanted all the brake lines to copy...so no bike for a week which isn't an option just now. But early in Jan i will get it done.
I have documented a little of the job for those interested. This forum has helped me a great deal already so keen to give a little back, which i will do with any other work i do in the future. Hope it is of use for others. Pictures below.
1. Removed the discs and cleaned off the lug faces
2. laid on the stainless shims
3. placed the disc (any tips on getting the discs centered? I got them to within about 0.3mm but that was a fiddle!)
4. Cleaned off the flanged bushes with some 800 wet & dry
5. found the flats in the bushes, marked with a red pen so i could make sure that when i re-assembled i could make sure a good face was in the right place.
6. Fitted new wave washers, fitted bolts, job done.