Frontline Flea & Tick treatment and Drontal Plus worming tablets are both recognised by DEFRA for the treatment of animals entering the UK under the PETS Travel Scheme. Treatment under this scheme is not for the benefit of the animals; it is to prevent diseases being carried into the UK which could be harmful to humans. However, as a pet owner, I want the best for my animals so I do not waste my time and money buying lesser products `off the supermarket shelf'. When in the UK, I stick to the recommended treatment programme but since the PETS scheme started we have frequently taken our dogs to France where we have family. In addition to the treatment required by DEFRA prior to our return, I always treat our dogs at the start of the holiday and I have had occasion to remove the odd dead tick during our stay. Consequently, I have no doubt whatsoever as to the effectiveness of both treatments.
After that, it is a question of getting the best price. There are various prices and P&P charges listed on Amazon. I buy a year's supply at a time so a low unit price can still work out more economical even with higher P&P charges. You simply have to work out which is best for you.