I have been to Cranebank a few times now and there is a housing estate next door, in between the Waggoners pub on the Bath road (Waggoners) roundabout and Cranebank. You can get to this estate by taking the next exit on the roundabout down the Bath road towards Meadowbank. Turn left into Burnham Gardens before Meadowbank onto the estate and follow the road back on yourself. This road goes into Westwick Gardens and then you can turn right into a road called Woodfield road on the estate, running parallel with Parkway A312, that runs from the pub to a primary school. Park near the school for free and walk (2 mins) to Cranebank!
Not entirely sure that the road names are 100% correct but once you are on the estate just head toward the general direction of Cranebank and you should find the primary school (Cranford Primary school I think?).
Good luck...