Not the most exciting deal in the world (and install will sure as hell itch!) but B&Q have 3 rolls of 200mm loft insulation (totalling 5.4m²) for just £5 - thats UNDER £1 per m² (93p) which is an excellent price for good quality Knauf loft insulation (and cheaper than the N-Power promotion).
I've just bought 5 packs for £25 (which, as you can see, filled my car nicely!) and there was quite a bit left at my local store (Yate, Bristol). I'd assume this was a nationwide instore event as it was all properly priced up.
If theres any left at the weekend you maybe able to get a further 20% off if you spend over £50, which would take it to just £4 per roll.