Curry's are all out of Samsung's but Tesco are now doing a £30 cashback + 8GB card, and there is no requirement to buy a case.
However, it appears that you can claim your cashback direct from Samsung as long as it was purchased from a UK retailer. Not all retailers have wised up to promote this, but it is valid as long as they are UK based :
Qualifying retailers: In order for your claim to qualify, your purchase must be made from a retailer specifically based and/or registered within the United Kingdom or Republic of Ireland. Pixmania are specifically excluded from this promotion.
This was the same when we purchased a Samsung Fridge Freezer. A few online sellers were promoting, but some, even big ones, were not.
We still managed to get £100 cashback an also a 5 year warranty, for free, direct from Samsung post purchase from a retailer that was not promoting this offer.
More info here :
http://www.samsung.com/uk/tab2cashback/