B&Q Paisley have 50% off all bulbs until the 19th june. When you enter the store go to the welcome desk ahd they have 50% off coupons there. They work with all offers even clearance.
I got Diall LED GU10 7.5w 480 lumens, 4 packs of 4. Already reduced from £16 to £12 per pack, bought 4 packs on their 4 for 3 promo and used the 50% off coupon and paid £18 for 16 bulbs. £1.125 per bulb. Cracking price for these and they are brighter than the halogens I replaced.
This might be national the coupon doesn't specify Paisley so may be worth asking in your local for a coupon.
The link goes to the ones I bought.
Just noticed on the coupon the code for online is BULB50 so it is national.