Someone might find this useful.
Boots have all the braun oral B electric toothbrush heads in the four packs for the same price the two packs normally sell for.
This includes the Sonic, polishing and usually expensive EB25 Floss action heads for their new toothbrushes. All normally at least £15.99
Not sure if it's instore.
If ordering loads of other stuff you may be able to find the £10 off a £50 spend voucher on this site and get extra points ontop.