Yes unfortunately RENFE is very costumer unfriendly towards Interrail users (EU Rail does not exist, if you mean Eurail, this Pass is for non-European people, UK is in Europe (the continent) and needs Interrail.)
I highly recommend before buying a pass to read the Information about the trains in the country you want to visit on interrail.eu. The terms of use on the trains are given by the company that run the trains and not from Interrail/Eurail, also there are now some problems to provide online reservations for Spanish trains.
About the first class, the main vantage, is to have more legroom or extra services, but not free reservations. If you want or need a reservation you have to pay, this is the same for 1st and 2nd class. Reservations are free on most trains at the station in Great Britain for trains there. But in all other countries you have to pay. Some places like Germany, Czech Republic, Austria or Switzerland have only a optional reservation, others you need a reservation almost only on high speed trains and in some countries also on long distance trains.
Thats the joy of travel. Other countries-other customs. And yes-these will be different from what you are used to on that funny island in the North Sea. There will also be NO extra food, free drinks or lounges for 1st over there. All these burocratic oversized state railways have their own rules and stick to it.
The poster mentioned that train operators in Spain do not recognize the Eurail mobile pass. Is that actually true? I am planning to buy tickets at train stations while I am there with my Eurail mobile pass for travel around Spain.
The poster mentioned that train operators in Spain do not recognize the Eurail mobile pass. Is that actually true?
I've never had any problems to buy a reservation for Interrail in Spain. Eurail is very much the same pass, only that it's for people from outside Europe.