How far in advance should I book train tickets from London to Barcelona?

The best time to book your train from London to Barcelona is <b>days before departure</b>. See how prices for trains change on the London to Barcelona route.预订从伦敦至巴塞罗那的火车，最佳时机为启程前数日。观察伦敦至巴塞罗那线路的火车票价如何变动。