I use drontal for one of my dogs. You can now buy it out of the chemist as well as the vets but the cheapest place to get it is online on one of the dog medices websites like pet meds or canine chemist.

My other dog gets panacur solution because she has a sensitive tummy when it comes to wormers. nothing else bothers her except worming products ... (You can buy it online too but if you have a large breed dog then it'll be harder to givebecause it's 1ml for each kg).