Edinburgh to London: try the seat reservation booking module on GWR or LNER (seat reservations in the UK are free!)

London to Paris: is possible. Very busy around Christmas and New Year, sells out weeks in advance. A couple of first class places left on one early train London-Lille (7:01 departure). Continue from Lille via TGV. Book asap or it’s sold out as well.

Bergen Oslo: use https://entur.no/ (select Eurail/Interrail in the passenger details)

Night trains count as one pass day, the day it departs. If you take any other train after midnight, you’ll need to use another pass day.

Edit, checked, 25 (=Christmas) and 26 (=Boxing day) of December are official holidays in the UK. There are no direct trains Edinburgh London. I don’t find any trains at all to be honest. I think only a very limited number of trains will run. Best leave a day later, or check busses.

You can find the Christmas Holiday period details of UK trains here: https://www.nationalrail.co.uk/travel-information/christmas/

There are hardly any trains in the UK on 25/12 and 26/12. Check timetables on www.nationalrail.co.uk.

The end of the year is possibly the busiest period for Eurostar. Eurostar have limited pass holder seats and many trains are not available anymore. For London-Paris, availability around 30/12 looks like this:

You can also travel London-Lille (1 train available on 30/12) and then further to Paris:

Lille to Paris still has many available trains. Book London to Paris/Lille ASAP, the best place to book is www.raileurope.com. You can also book Lille-Paris there.

Bergen to Oslo can be booked free of charge on www.entur.no.

A night train only uses one travel day if you stay on the same train after midnight.

In general, use this page as a guide to book reservations:

https://www.seat61.com/interrail-and-eurail-reservations.htm

For Edinburgh-London megabus has a direct service leaving at 11am for 52£. You should book it ASAP.

London-Paris: you have available ferries in case (notably Newhaven-Dieppe) but it will be a full travel day… https://www.seat61.com/trains-and-routes/london-to-paris-by-ferry.htm As said book ASAP. For example there’s a 4pm ferry out of Newhaven for 31£.

Thank you very much 

There are hardly any trains in the UK on 25/12 and 26/12. Check timetables on www.nationalrail.co.uk.

The end of the year is possibly the busiest period for Eurostar. Eurostar have limited pass holder seats and many trains are not available anymore. For London-Paris, availability around 30/12 looks like this:

You can also travel London-Lille (1 train available on 30/12) and then further to Paris:

Lille to Paris still has many available trains. Book London to Paris/Lille ASAP, the best place to book is www.raileurope.com. You can also book Lille-Paris there.

Bergen to Oslo can be booked free of charge on www.entur.no.

A night train only uses one travel day if you stay on the same train after midnight.

In general, use this page as a guide to book reservations:

https://www.seat61.com/interrail-and-eurail-reservations.htm

Thank you very much