There’s a lot of pretty good guides available online to help you check how good (or bad) various types of food are.
Unfortunately a lot of them are quite boringly presented ie. lots of tables of data and not much in the way of visuals.
This site, however, is pretty simple to use and incredibly visual.
It’s not as comprehensive as a lot of the bigger sites and guides, but you can immediately see things like Pringles being much worse for you than Walkers.
Louie / Personal Trainer
Not a bad website but a pitty it doesn’t work at all in Internet Explorer.