One thing to remember when booking through lastminute.com is that they add (or used to add) a surcharge for paying by credit card. This may or may not be higher than BAs surcharge.

OTOH booking with LM using the Tesco link http://www.tescotravelstore.com/ earns Tesco Clubcard points at 1/£ (or used to).

I say 'used to' as I haven't used them for some time following a bad experience some years ago. They may be better now.