Put in some Shell V-power & give it an Italian tune up after the car is heated up.

So, as i read it, you leave work and have to climb a decent hill a few seconds later, correct?

I have no idea of the timing of glow plugs these days, but i wonder if the loss of power is happening at the moment the glow plugs switch off, so you arn't losing power as such just that the cleaner cold fuel burn helped by the warmth of those plugs is suddenly lost, more noticeable because you are using all the power to climb that hill.

Alternatively, it could be that the extra fuel injected when the engine is cold is cutting back to warm engine running at that point.

This is all theory of course and i am probably well off the mark, but it might an interesting experiment to let the engine run for a minute or two longer before starting your hill climb and see if there's any difference.