Unfortunately, the people in airport operations aren't necessarily as clued up on these rules as airline ops and flight crew. I have witnessed a situation when a Cat 1 destination went out of limits (un-forecast) and ATC announced that three of the possible four available alternates in the country were not accepting diversions. Until pressure was applied through ATC to bang some heads together at these airports, none of the three aircraft holding had a diversion available. Airport ops seem to base their diversion availability on whether they have enough handling staff, steps, chocks etc rather than the fuel planning rule that simply requires a strip of concrete and some kind of instrument approach.
Although there are a lot of runways available in the UK, there is a creeping tendency for airports to declare themselves unable to take diversions or even more vague they are now saying "may not be able to accept diversions" and this make planning around minimum fuel strategies even more complex. This can be a problem early morning with widespread fog and when many airfields don't produce TAFs until after opening time. Also, do ATC take into account the availability of Military / industry airfields in the unlikely situation where there is a major failure and everyone just needs a runway to get onto pronto? I am thinking Brize, Waddington, Hawarden, Warton, Lossiemouth etc.
These minimum fuel rules only work when every stakeholder understands them and knows how to apply them.