M&S has prebagged produce. The amounts can be a bit too much for some, but the prices are insane. On recent weeks specials I have gotten 2 pounds of grapes for $1, a pineapple for $1, and so many other great deals. While the produce is a good deal, the deli is exceptional. Each week brings several great specials. There is always a line, but there are several people behind the counter and they keep it moving. You can also call ahead and your order will be waiting. The staff is knowledgeable if you need info on a product, or if you need to feed a big group they can advise on how much to buy.
M&S does so much business that freshness is never an issue.
Finally, even if the deli product you want is not on sale their regular prices are so low that you just cannot beat them!