The old style 'spicy spaghetti' in the white packets are manufactured by a French company, Bariatrix, and also sold under the name Dietimeal - so yes, they're the same. The cottage pie, choc truffa and lemon bars are also made by the same company - plus maybe others but they're the only ones I've bought and can confirm are in identical packaging, nutritional info etc
You can order smaller volumes from SnS too - not sure whether dietimeal will work out cheaper - probably depends on exact volumes you are buying. Avoid the Dietimeal snakck bars though - they won't help on a VLCD.
I ordered 21 items from slim and save in the end, worked out cheaper as I didn't need to order boxes of 7 and could try a few things, even ordered a famous truffa bar!