The train from London to Edinburgh is a popular train route. It's also one of the most expensive, which means it can be difficult to get tickets for this trip. If you're planning on travelling by train between the two cities, here are some tips to book London to Edinburgh train tickets at Rail Online:

Book ahead: The best way to get the cheapest tickets is to book early. However, if you want to be sure of getting a seat, then you must book at least two weeks in advance – or even longer if possible. This will allow time for any cancellations or delays and means that there are no gaps in your schedule when tickets can be purchased on short notice. If booking online then try checking train times before booking as some trains only run from certain times of the day so it might not be worth purchasing at peak times even if they are cheaper.

Travel midweek: If you're planning to travel midweek, it's best to book your train ticket in advance. The train is less crowded on the weekdays and weekends, but it can still be quite crowded during the summer holidays.

Avoid peak times: Avoid travelling on Friday or Saturday if you can. Even though these days are popular for train travel, they're also the busiest times to get tickets as most people will be travelling to see friends and family at this time of year. Avoid travelling during the summer holidays if possible—your best bet is to book your ticket as early as possible (and it's always advisable to book far ahead). If you must travel during this period, choose an alternative route. Finally, avoid booking any tickets during Christmas and New Year's Eve weekends due to congestion at stations along major routes like London–Glasgow trains because there aren't enough seats available throughout these periods when demand peaks due largely because many people who were planning on travelling home after Christmas break want first use those seats before heading back out again at some point in January when many others come back from holiday time off work/school etcetera.

Travel first class - if you can afford it: If you can afford it, travelling first class is always the way to go. It's more expensive but also more comfortable and offers better food and service. First class is also less likely to get delayed or cancelled, and if it does happen, you'll be compensated more than a coach passenger.

Follow these steps to book your train tickets:
o Book as early as possible. The earlier you book, the better chance you have of getting a good price and avoiding peak times.
o Book during the week. If possible, try to avoid booking at weekends or holidays when prices are higher and trains are more crowded.
o Book in advance if possible—especially for long-distance trips like this one from London to Edinburgh (which takes around four hours). You'll also want to make sure that your train ticket is valid for at least two days after travel (so it's worth checking this out before buying).

Hope these tips have helped you to book your London to Edinburgh train tickets. The best advice is always to do your research and know what you are looking for when buying train tickets. As a passenger, it’s up to you to choose the right journey and budget for yourself, but also make sure you're aware of any potential pitfalls along the way - like booking at the last minute.