Upcoming Flight to Cancun

Hi all
Discovered this forum by accident, but glad I did so.
My wife and I fly to Cancun on Tuesday, 10 July in PE.
We have previously flown from LGW with VA on a few occassions and now we have enough miles to upgrade to Upper Class.
I called VA some time ago, however, we were advised to request an upgrade using miles upon check in, which of course we will do.
My question concerns which plane we will be on, particularly as the config given in the seat plan is the 747-400 and not the LGW fleet. Would I be correct in assuming that VA must have one of the LHR fleet covering the absence of others undergoing refit.
Has anybody else had this experience? It would be great if we are on one of the more modern fleet!
Discovered this forum by accident, but glad I did so.
My wife and I fly to Cancun on Tuesday, 10 July in PE.
We have previously flown from LGW with VA on a few occassions and now we have enough miles to upgrade to Upper Class.
I called VA some time ago, however, we were advised to request an upgrade using miles upon check in, which of course we will do.
My question concerns which plane we will be on, particularly as the config given in the seat plan is the 747-400 and not the LGW fleet. Would I be correct in assuming that VA must have one of the LHR fleet covering the absence of others undergoing refit.
Has anybody else had this experience? It would be great if we are on one of the more modern fleet!