Okay, a little perspective.
Switching from CD (which I have also done before) to Atkins you will very likely gain weight in the first week. Hopefully not much but you need to be prepared for a gain, and possibly for spending the second week just losing that gain. Some people are luckier than others with this but it's best to be aware, you can't go from not eating to eating without your body taking a while to adjust.
You won't see the big first week loss many people on Atkins see - that cones from losing your body's water stores, which you've already done on Cambridge.
Once you're losing, expect to see losses between 1 and 3 pounds per week. Sometimes it may be more, sometimes less.
'Free' food that you can eat as much as you like of means basically meat and eggs.
Salad is restricted to 3 large handfuls of mostly green vegetables per day, and you need to count the carbs on these.
Count the carbs on everything but meat and eggs. You want to stay under 20 grams of carbs per day and 15 grams of this should cone from veg in the Atkins ideal. There are 4g carbs in one courgette, for example.
Unless you're on a later stage of the diet (slower weight loss) fruit is a no-no, as are higher carb veg like peas, carrots, tomato and corn. No bread, pasta, no rice or potato etc.
You can have cream and cheese, but not too much, and bear in mind done people don't lose weight if they eat even the allowed amount of cheese.
The Atkins bars are not free food - they can contain between 2 and 5g carbs. Some people are okay having one a day. Some people can't have any or they don't lose weight at all. Bars and the sugar free sweets you'll see mentioned contain sugar alcohols, which stall a lot of people.
Take a look at the sticky about cheating, which explains why even small high carb treats can be more harmful on this diet than a low calorie one. If you're the type to treat yourself for being good, it's not ideal.
For me it's a great diet and easier to stick to than Cambridge at this point in my life but it is a commitment and you probably will still feel deprived of some things, or get sick of eggs, etc etc. And the losses are slower than Cambridge.
I really don't suggest rushing into starting until you've read the book and got yourself prepared, or you might find your efforts thwarted by small mistakes early on.
Good luck whichever way you decide to go!