Probably not all accounts, possibly not stocked by some Sainsbury's. Saying that, I've just bought some in Sainsbury's Leigh, and I've failed to find all the other recent /current Sainsbury's freebies, it's looking hopeful :)
* offer is running until the end of 28th August.
Good news is, it's free after cashback, and if you're nearby, it's got to be worth popping in.
It's been on offer showing an amount of cashback on checkoutsmart for a while, so a decent chance you could find it in stock.
It's the 350g size, which seems to be the only size listed on Sainsbury's website