The East Japan Pass covers the whole area to the North East of Tokyo – including the Narita Express (to and from Narita Airport) – up as far as the ‘Seikan’ Tunnel which joins the main island of Honshu with the northern island of Hokkaido. Currently the pass available is a 5 day flexi pass, which can be used on any 5 days within a 14-day period.
The JR East Pass is sold as an “e-ticket” (like an airline ticket), not a physical voucher. THE GBP £ sterling price is determined by the airlines’ reservation systems at the time of purchase.

It can be bought on this website, online from JR East or within Japan, at Narita Airport as well as Tokyo, Shinagawa, Shinjuku, Sendai and many other JR East stations.