There's a bit of a trick to standing for 2-3 hours at a time, and that's to not really stand. I think I was taking it too seriously. Lean, stand on one leg, dance a little, or a lot, stretch, loosen up and be less formal about it all. Cutting in an hour a day seated laptop work in the lounge also helps. It's not supposed to be a trial of Hercules.
Now, I'm loving it. Stage 2 is definitely go once finances permit. 12 miles around Mam Tor at the weekend (in the rain, may I add) proved I can still put one foot in front of the other for a few hours on the trot. Lets see where this goes.