Its all clearly in the site: you are on such a pass allowed 1 day for a trip OUT (or even to airport or seaport) and 1 day for IN. Does not even have to be very 1st/last, but for most thats natural.

There have been a very few postings from Brits that-as such a pass may even be cheaper as a full-fare super-expensive return from your home to :LON on the most expensive train they have-that staff ask for proof that you indeed leave that funny island in the NorthSea that day. The next hurdle is getting a seat REServed on the €*-read the many postings about that