Yes, Tesco does sell tens machines. You can find them in the electricals section of most stores. They usually have a good selection of different models to choose from, so you should be able to find one that suits your needs.
Tens machines are a great way to relieve pain, and they are also very easy to use. Simply apply the pads to the area of pain and turn on the machine. The electrical impulses will help to block the pain signals from reaching the brain, providing relief.
If you are looking for a Tens machine, then Tesco is a great place to start your search.