I have a freee coupon for Spain and a chance of a trip in the next 72 hours
Free coupons are not valid on express trains in Spain - only the long distance all shacks EMUs and DMUs (these are surprisingly popular for long distance travel with people on limited budgets even with the 3+2 seating on many of them plus the lack of luggage space - not recommended if they can be avoided). You need to take your FIP discount card to obtain a global price ticket that includes the fare and the compulsory reservation for each express train you wish to travel on.
When I last visited Spain I booked most of my journeys in advance through the DB people at Surbiton. The tickets proved to be very cheap for the distances travelled (something like 10-11 euros per train). This obviated the need to queue up at stations to buy FIP tickets and reservations (leave plenty of time if you have to do this as the queues at some stations can be horrendous - watch out for those stations that have a queueing system that involves taking a numbered ticket from a machine and waiting for this number to be called).
Keep your free pass as a back up in case you need to use a stopping service as a connection or visit some of the remaining long distance non main line routes. Don't forget to take your FIP reduced rate card with you to show the ticket examiners to show proof of entitlement. I left mine at home once and got chinged 70 euros as a result to travel from Barcelona to Madrid.
As an aside it is a requirement at some of the major stations to put your bags through a security detector as you do at airports before you are allowed on the platforms to board your train.
