1. Do a mileage run (the famous LON-BCN-AGP/SVQ and rtn). 2 of these would net you all the miles you need. Or you could combine one of these with an I class deal to Italy.

The problem here is that the run is on Iberia and there could be a delay in getting the miles to post.

If it were me (apart from coming back Club) I would book a £1,400 BA ticket. This is the equivalent of getting a BA Miles overdraft. BA makes a few quid interest by sitting on your money for 2-3 months, so don't feel too bad about doing it.