@cyclealex: Would be more open to cycling on the road if you could at least tell where it starts being two-way...
I think it's two-way everywhere except for the short stretch where there's the right-turn bus lane and the left-turn other traffic lane. Certainly there are no "no left turn" signs for traffic leaving the premises on the east side of the road, and there is at least one 20mph sign (haha) facing towards traffic heading southwards from that point (here).
There is a shared use path sign*, plus a dropped kerb, at the exit from the retail park service yard behind Decathlon, facing traffic heading northbound (here). So I think it's pretty clear that it's shared use at least that far south from the T-junction. There is also a dropped kerb on the south side of that exit road, but whether that is any reliable indication of cycling being allowed I don't know (presumably dropped kerbs at junctions can also be provided for wheelchair users).
Given that there is no "no right turn" sign for traffic leaving the service yard I think it's safe to assume that the road is two-way from at least that point southwards.
* Note that it is a "flying bicycle" shared use sign, not the sign for a path with segregated pedestrian and cycle lanes. Thus I believe that any remnants of white linage on the path are obsolete.