Bit of an update with my problem - taken a while because I learn't to drive round my wobble as it only did it under light braking- that and finding the time to fix a non serious issue is difficult!
Anyway- penciled in a money throwing exercise - starting with two new back tyres and a referb of the wheels. Suspected one buckled front- found one front and one rear - so got them all refurbed job lot. Anyway I fitted the wheels myself- lazily used a rattle gun... still had the brake wobble and seemed to have a slight wheel balancing problem so got them checked at the wheel refurb place- they were slightly out so got then sorted- then fitted the wheels, albeit properly with a torque wrench.
On the drive home the car was perfect- really smooth/vibration free and weirdly my brake wobble has gone... Which is good because I was about to change the hubs/ discs / control arms- I'm still suspicious it may return though but goes to show how sensitive these car are. I think i'll change the control arms anyway and do a wheel alignment for piece of mind and to keep the tyre wear even.