Pay or Chance it?

I have 3 K-class seats booked for Dubai on the 14th October.

I'd like to upgrade one way to UC, and have the points available. I understand that if I do this in advance, then I will ave to pay, up to £300 per person, to make the ticket upgradable. Also, there is currentlu only 1 UC seat vailable for upgrading, although the advice I have had from the sales desk was to check again a week before, and some more may become available - the number of free seets was making this look likely (remind me - where can we check this?)
So, do I grab any seats as soon as they become available (if they do), or, do I stay cool, and turn up at the airport and blag a miles upgrade, and hope that the nice desk staff don't ask me for the £300 a seat to do so?

What would the panel advise? [?]

[preiffer]

I'd say, from recent reports, the chances of "blagging" a miles upgrade without buying up to a higher ticket are diminishing by the day. They're getting more and more controlled in terms of how the upgrades are handled.