Off the shelf flea and worm treatments such as Bob Martins are not generally very effective. Most people use a combination of treatments for internal and external parasites - Frontline to deal with fleas and ticks and something like Milbemax or Drontal for worms. Frontline is expensive but you don't have to apply it all the time, I get the spray as opposed to the spot on and I only use it on my dogs in the spring and summer which is 'tick season', they've never had fleas. I pay about £6 for 3 Milbemax tablets from the vet; the rule of thumb for worming is once a month up to 6 months of age then again at 9 and 12 months and then every 6 months after that.
