If any of the flights you're looking at have award availability, you can buy the miles you need for a one-way upgrade (12.5k) to J for £223 (though the flight will then earn you less TPs and miles than buying J so the "true" cost is a little higher).

In theory you could upgrade both ways for 25k / £446 subject to award availability, but you can only buy 19k each for yourselves. The solution would be to find two friends to gift 13k miles and get them to upgrade you.

Shame you didn't ask this last month: AA had a promotion that could have got you a CW return for £750, though I think that would involve a bit of delay/chance.