You have to full travel days to get in or out of the country, indeed a 24h period. You can technically use the two days to get out of the country, but you need to fix ordinary tickets to go back to the UK.  You won’t have any in/outbound days back.

When are you planning your travels? Eurostar is heavily booked these days, getting even worse in the Christmas Holidays. It’s a bit better after the new year.

If you can manage to get the cheapest Eurostar tickets, it’s about the cost of a pass day + reservation. So you wouldn’t need to use the two days.

You have a maximum of 2 travel days in your country of residence. You can use both of them, e.g. to spend a few days in London, but then you won't have any left for your return journey and you'll need to buy a normal ticket for Eurostar and the connecting journey. You can still use a ferry with a discount (e.g. Hoek van Holland - Harwich), as long as it's within the validity period of your pass.

Actually a travel day is not any 24h, but from 00.00-23.59 CET, which is 23.00-22.59 GMT.

Depending on your home town (Mine is Leeds), if looking for time in London or nearby I would be looking for an advance saver fare to London rather than use a pass travel day. Then use the first UK travel day for Eurostar - remembering if yo actually stay outside central London - you can use your pass to get you to St Pancras for Eurostar on the same travel day.

I assume you would then return E* and connect with train(s) to home - again on a single pass travel day (your second UK day)

There is no such thing as an “Advance Saver” fare. Please do not confuse people by garbling what are often complicated fare terms.

“Advance” is the name given to fares issued across the GB rail network that are sold for use on a single fixed departure (and sometimes connections) and cannot be used on any other train. These are usually but not always the cheapest fares for a given journey the trade-off being the strict restrictions on use.

Advances always come with reservations for the specific train(s) which must be taken and these reservations need to be shown along with the ticket.

Ignoring these restrictions and using a different train is effectively travelling ticketless and can lead to a demand for a new full-fare ticket to be purchased.

“Saver” is an old term that still gets used in places for what are now called “Off-Peak”, tickets that have some time restrictions but are not set to any specific train or in the case of returns any particular day within a period (usually a month).

These will often come with reservations but these are not mandatory and can be ignored if the passenger wishes to use a different train, as long as it does not break the peak restrictions of the ticket.

I stand corrected on terminology, but the principle is still valid - you either use both pass days on getting to London, staying a few days and E* or you travel down on the lowest available price ticket .

I think most Brits would realise the cheapest fares are fixed to one train. Also peak time trains are the most expensive and off-peak are cheaper.

BEWARE. This company is aweful.