There are several points on the North Norfolk coast where you can see seals. You may be able to see them from the beach at certain points - you could try the areas around Sea Palling or Horsey - but most visitors prefer to take a special boat trip to areas where you are almost guaranteed to see seals.
The most popular seal watching tour is at Blakeney Point. This is in an area run by the National Trust and is an important centre for wildlife. You go in a traditional wooden boat which brings you as close to the seals as you can get without disturbing them. Good times to go are June to August, when the common seals have their pups, or November to January to see the grey seal pups.

A similar tour, and also very popular, is from Morston. You can learn more about the seal watching tours here.