I've only just started it (online) so am getting used to it and there are a few bits I don't understand, but the basics are:
-Unlimited Free Foods all day every day (these are lean meat, eggs, fish, fruit, vegetables including potatoes, pasta, rice/grains, beans/pulses and some fat free dairy products like fat free yogurts). You can eat as much of these as you want. Sugar free drinks like Diet Coke, No added sugar squash or herbal teas are also free. You can drink tea and coffee but would have to count the Syns for any milk or sugar you add.
-Healthy Extras, in addition to your free foods you pick one Healthy Extra A (a set quantity of milk/cheese/dairy with fat in) and one Healthy Extra B (a set quantity of fibrous things like cereal/bread/dried fruit/crackers/nuts or seeds)
-Syns are anything else that doesn't fall into the category of free food and is in addition to your healthy extras. For example and cooking oil, mayonnaise, pasta sauce would have a Syn value. Chocolate, biscuits and really anything processed would have a sin value. You get 5-15 Syns per day to use as and when you please. if you have a goggle you can find out the sun value for your favourite foods/snacks.
In answer to your questions:
Yes you could use the Hairy Bikers book but when making a recipe you would need to count the suns of anything you use that isn't free food and then divide that by the portion you eat. Alternatively there are lots of Slimming World recipe books or online recipes which give the sun value (if any).
Yes there is a food diary
No there is no calorie counting, only food recording and Syn counting.
I personally like slimming world because it is quite brand focused. If you search their Syn calculator it tells you the total for most items. Not only from scratch ingredients but specific items like Sainsburys Cheese & Onion crisps or Walls Mini Milks. If you're on the go with a baby and find yourself needing to grab a snack you can either eat fruit without the calories or do a quick search on your phone to see how many sins something is. Plus allows you to be social and eat out. No special meals for you. Its already making my life really easy.