Lots of ifs, but:
IF you have an American Express card.
IF you get an itinerary fully on e-tickets.
IF you can use an address in the country for 'delivery' (actually delivery of nothing at all...)
Then you can book using
www.opodo.co.uk with any billing address. If you're booking BA or BD ex-UK, though (and can manage a little French),
www.opodo.fr offers cheaper rates.