Seat reservations within Great Britain are usually not hard to get, especially through LNER and GWR's booking systems. Both 2nd class and 1st class seat reservations are available for everyone, but please note that a reservation for the right travel class is required.

Eurail reservation self-service system

• Eurail 
  • Eurostar (International tickets) only

Administration costs when booking through Eurail self-service

• € 2,- p.p.per train
• Additional € 9,- per order (for paper tickets)

With railway carriers

• SNCB (b-europe): Only Eurostar trains
• LNER (London North Eastern Railway): Domestic trains
  
  • Please note that a reservation for the right travel class is required
    
• GWR (Great Western Railway): Domestic day-trains 
• Caledonian Sleeper: Domestic night train (For a seat reservation you need to contact the Guest Service Center) 

Other platforms

• Rail Europe: International trains
  • Eurostar and connecting TGV trains from Paris and Lille
• ACP Rail: Domestic trains and Eurostar trains to Belgium, France, and the Netherlands
• Railtourguide (UK based travel agent)

An explanation of how each booking platform works can be found here: How do I book my reservations

Locally at the train station in Great Britain

Good to know

Eurostar: All customers with a Global Pass are eligible to travel on the Eurostar (between London and Paris, London and Brussels, and London and Amsterdam/Rotterdam respectively), with a compulsory reservation. However, the Eurail Great Britain Pass is not valid on Eurostar. Reservations in Great Britain can be made online at ACP Rail (€6) or locally for free. Reservations are free for only LNER.

Reservations for Eurostar can be booked through

• Our Reservation Service 
• The Rail Planner App
• Via the B-Europe website
• Via phone at the Eurostar booking center (+44) 01233617575 (outside the UK) or (+44) 03432186186 (within the UK)
• Directly at Eurostar terminals.

Note: Bicycles are generally allowed on British trains, but conditions vary between companies.