You have two days to get in or out of your country. Usually that’s the first and last day of your trip. On such a day, you can take as many trains as you want to get out of the country. You can also get to a ferry port, or airport, bus station… Leaving doesn’t necesirally need to be by train.

A pass day is valid from 0:00 unit 23;59 (but you can finish a trip that started before midnight, until after midnight, like your trip with the Caledonian sleeper).

But to get out of London with the Eurostar, you will need an extra pass day if you want to do that by interrail. So you’ll use up both days to get out of the country, so there’s no way for you to get in the country any more by train with your pass.

Since it’s for next summer, you can book well in advance and score cheap Eurostar tickets of +/- 59 EUR, comparable to the cost of a seat reservation and pass day (30 EUR +cost of a pass day) to avoid losing two days on one outbound trip or book the sleeper tickets and use the pass days on the Eurostar.

Depends what makes more sense to you cost wise :)

If the sleeper departs before midnight 00:00 you will use up both the two days of travel in UK. Your only option is to take an early train to London or pay the full fare on the sleeper. For travellers from Scotland it is often better to pick up a cheap flight to the European mainland

The previous 2 replies are not entirely correct.

For sleeper/night trains through Europe the convention is that any train boarded before midnight is counted for a days pass use on the boarding date only.

EXCEPT for Caledonian Sleeper who flip it and insist the arrival date is the one requiring a pass day to be used not the boarding (before midnight) day.

That would work to your advantage to travel sleeper-eurostar as it would all be on one pass day.

However, the mobile pass is set up to apply the standard european convention not the CS alternative way so if you try to use it correctly it will take both your inbound and outbound days.

Definitely a situation where I would opt for a paper pass and travel diary over mobile pass and app.

The other thing to bear in mind is that for sleeper berth accommodation the price difference between booking an all-inclusive Caledonian sleeper ticket and just a reservation supplement for an interrail pass can be small. You can look both up and book berths at www.sleeper.scot

In addition, the mobile pass uses CET/CEST. That means a travel day on a mobile pass runs from 23:00 GMT until 22:59 GMT. Since the sleeper leaves Edinburgh at 23:40 (= 0:40 CET), that means it already uses the day of arrival.

Really good to know this all for the Caledonian @Al_G and @rvdborgt ! I also learned a lot.

Unless you are hell-bound to go on iron monsters over rails-consider also the pretty nice Newcastle-Ijmuiden ferry (DFDS, still nice to foot-pax) with direct connecting bus to that city that does not want tourists anymore-and even less so from UK. All in all might even cost less as the allovertherails +surcharges.