Doesn't sound like a great deal but right now you can get 30p off of any Red Label tea product at Sainsburys.
As part of the fairtrade promotion (Red Label is a FT tea) you can pick up a leaflet with a 30p off voucher from your local sainsburys. The good thing is you can use it on any Red Label product and you can use one voucher per product. I saw something for about 75p so a 30p discount would be 40% off. You can also get two packs of loose (2x85p after discount) tea for less than the price of a twin pack (£1.90 after discount).
I found the leaflets at the customer service desk so presumably that's where you'll find it in other sainsbury's. They also have 500g McVities Digestives for 50p which goes nicely with the tea