Currently I have H&R cup kit fitted to my Bora, but the ride albeit pretty good on most  roads I spend every day driving around London and this set up is just little to unforgiving for the capitals appalling roads and huge speed bumps.

I've been thinking of switching to something a bit softer and was wondering what the B12 kit is like, any opinions ?

As an alternative to H&R would go for Bilstein B4 (Sports) & Eibach Pro Kit rather than B12.

B12 first class kit but not what you are looking for here in terms of comfort levels.