The best lowcarb cookbook is the net!!!!! There are so many great recipe sites available that NO book can match up. I save the recipes I find to a folder on my desktop and try out something different at least once a week.
Unfortunately, I don't think that Dreamfields is available in the shops in UK, nor is gluten flour. If anyone knows otherwise, they will let you know. Ground almonds (an absolute staple for LC) is available everywhere, as are linseeds and other nuts you can chop or grind yourself. Most other stuff is just frankenfood, like LC choc bars, so if you want those there is bound to be more choice in big stores. I would be careful about those - some of them are revolting, not to mention outrageously expensive. Hopefully someone else can make a recommendation for you - low carb Rolos are quite nice, probably the best to my mind but can be bought here, too.
If you want to order online, I'm sure you could send a cheque or a money order - that's the best option IMO.
Babs