I have been using the hotels.com/britishairways portal for my last few bookings, since the cashback from Quidco or TCB has dropped so much. So far I've had (I think) 3 successful transactions, out of 3 attempts. The Avios for all three have posted as expected a few days after the stay. I'm hoping the next 8 bookings I have all go the same way!

Having said that, the Hotelscombined route mentioned above looks like a better deal for the future (while it lasts!)