If you are on an inflexible business class tickets, sadly I think your chances of moving your flight are pretty slim, as BA are pretty draconian on not allowing any changes, in an effort to protect there flexible fare revenues
If you are on a flexi ticket, then I would simply keep checking the award availability for your wife's ticket upto and after your arrival at LHR. If you have a flexi ticket and there is space on earlier flights and you're nice and polite, I suspect you may have some luck getting moved up.
Otherwise get tge wife to the spa and a nice spot in the lounge from which you can enjoy the gloop!