
Over the counter products from PAH are unlikely to have such a decent result as a vet recommended product. However, there are canine chemists online who will be able to supply at a far better price than your vet.
I won't use a spot on as I refuse to worm my dogs on a monthly basis. Having left 3 Collies unwormed for a year, and then sending faecal samples to Langford, to find out that no worms were found. Obviously, it's a case of working out what risk your dogs are taking. Where they are walked/run etc.
As to flea products, I only use a Frontline spray (prescription needed)
when I see a flea. Not at any other time. It's worth mentioning that I haven't used Frontline in almost 5 years.
You are going to get different opinions, depending on the experience of members. I like two different products, and won't combine a worming and flea treatment together, so flooding my dogs bloodstream with chemicals. I just won't take the risk. I use Panaucur for worming youngsters and Drontal for adults. But my adults rarely need the treatment.