My son lives in La Linea (next to Gibraltar) and we would like to fly to Barcelona in July, stay a few days and then travel to San Roque (his nearest station) by train and then return to Barcelona after a week. Our travel agent failed to find any information. Is it possible to book this in advance or should I wait until I get to Barcelona? J.A.Bradby, Oldham

Sunday Times travel expert Richard Green writes: Once you know who to talk to, it's easy booking Spanish rail journeys from the UK, and yes, you are better off booking in advance - or at least doing some research on the routes, times and fares, before you go.

Spanish Rail Service (020 7725 7063) are the UK agents for Renfe. Its biggest sellers are the high-speed trains between Barcelona and Madrid (from 2hrs 35minutes and £93 one-way) and from Madrid to Malaga (from 2:30 and from £59 one-way).

However, they can talk you through the nitty gritty of where best to change and what time train to get on any routes on Spain. You probably won't be surprised to learn that there isn't a direct train from Barcelona to the little station at San Roque, so the best way is to change trains in Granada.

It's an 11-hour trip to Grenada, which sounds to me like the perfect excuse to spend a couple of days there, or at least enough time to visit the magnificent Alhambra Palace.

There is a day and an overnight train from Barcelona for £43 and £111 respectively. The daytime fare is for a seat in standard class, and the one overnight is for Grande Class, with a two-berth cabin with en suite facilities, dinner and breakfast. Still in a two-berth cabin, but without en suite or complimentary dinner, it's £80. Trains from Granada to San Roque take about four hours and cost £15.

I know I shouldn't say this, but you could fly back to Barcelona from Grenada with Ryanair from £40 one-way. Or from Malaga try Click Air and Vueling.

Spanish railways (Renfe) have a good website at www.renfe.es - select English at the bottom left of the page, next to the purple clock face symbol. Note that via the Renfe site, or through Spanish Rail Service, national inter-city trains are bookable from two months in advance, and regional trains only from 15 days in advance.

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