I doubt they are mandatory as they are not the regulation size. By far better to exit onto Stockport Road than the idiots I've seen exiting onto Church Lane and then turning left.
I alluded to the "courtesy" no exit sign onto Stockport Rd. I readily accept that this instructional sign is on private property and whilst it might not be enforceable, I think the prosecution would have a strong case if an accident happened there as a result of a vehicle emerging onto Stockport Rd.
As you come out of the Petrol station onto Church lane the blue sign in the refuge indicates for vehicle to turn right thus joining the flow of the one way St. Turning left creates confusion to approaching vehicles and should not be done. Having said that, I have seen the Summerfields HGV delivery vehicle doing just that- a fine example.
So in order to use the petrol station coming from Stockport, Stop in the refuge in centre of road, wait for oncoming vehicles to clear-also keeping your third eye open watch out for the speeders coming round the bend out of Station Rd and then turn in. When you have filled up, go and pay (don't forget to lock your car) and then turn right into Church lane, then finalise your route at Littlewoods roundabout- SIMPLE- geek!!!!!!!