Snapper, as an afterthought, since you are shooting in the U.K. and may not have as much sun as I do here in Tucson, consider an N+1 development if there is a very overcast sky or flat light. If you add about 22% to your times, you will be very close to N+1 with Efke 25 and PMK. I use this in landscapes here in the desert if there is no real white in the scene. A yellow filter and N+1 development will help with that extra bit of contrast you may need in some shots. The hard part with this development is that you are using roll film and not sheet film. In 4x5 or 8x10 it is much easier to control development on a shot to shot basis.
Please let us know how things go with your trials and tribulations.