It will be impossible for you to work out the syns in a food WITH a free food allowance without access to the syns calculator, as it is very complex in how it works out the syns, and takes into account a number of factors.
For snack type items though, you can use 1 syn for every 20 calories, so for things like chocolate, biscuits, icecream etc, that have NO free food allowance.
There is a US Slimming World site being released in the Fall, which will have US based information, so you might find this more useful, as a lot of products available in the US are also available in Canada. I would also check out the overseas section on here, as there are some stickies which may or may not help you.
Slimming World is not really about counting calories, it is about a combination of high satiety foods. If you do extra easy and make sure a 1/3 of your plate is superfree foods (veg or fruit, excluding parsnips, avocado, peas and sweetcorn) then you naturally limit the other higher in calorie free foods, without the need for weighing or caloring counting. Of course, like any eating plan where your aim is to lose weight, you need to learn to recognise when you are satisifed and not eat food just because it is free.
Good luck!!