Don’t worry, you won’t have a problem speaking English there.
From my experience flying around Barcelona area is that private pilots generally speak english but the problem at uncontrolled fields is with ULM. Most of these guys don’t speak english and sometimes don’t even bother communicating in any language for that matter. It happened to me at a couple occassions that I was communicating my position and intententions in English with zero response. After 2-3 calls I gave it a try in Spanish and suddenly got 2-3 other pilots on the radio communicating back and all were ULMs..
What I have found is that a lot of the time in the Pyrenees nobody can hear you anyway. IIRC you are supposed to talk to Barcelona Info (?) but most of the time there is no response, and flying north the first unit you get is Toulouse who ask you if you are VFR or IFR 
My take on it is that there will be little local traffic there at the end of Sept, especially on a Friday. If any, likely glider activity and certainly the tow plane pilot will be able to speak English.
Thanks for all the feedback on speaking English. Much appreciated and all very helpful. So, English it is then.
It would still be interesting to understand the regulation for small AIP-listed airfields in Spain better, if there is any.
People often complain about France, but at the very least, it is very clearly documented in the AIP which airfields are mandatory for French (and when) and which ones aren’t.
For example, I have read that at La Axarquia, local pilots start bitching when somebody comes and makes position reports in English.
Maybe worth a different thread.
@boscomantico there isn’t any ‘SP-only’ attribute to any airfield, AIP-listed or not.
But indeed many, maybe up to 50%, of PPL-holders do not dominate English well, especially those who have learned to fly at Aeroclubs. Most don’t leave the country and Spanish is an official RT-language. This percentage rises to probably 95% for UL pilots.
I’m not aware of any ‘discrimination’ as per your example of LEAX, but my experience is limited because I use Spanish, unless there’s a gringo around of course 
I would say that most pilots will do their best to switch to English in such a situation, within their possibilities..
Have been in an awkward situation though when flying to a field in Catalonia once. Other pilot in the circuit refused to speak Spanish and used Catalan. How about that for putting politics over safety.. I would like to think this as being anecdotal and it won’t happen at our LECD fly-in.
@coolhand @speed @Antonio please add and correct as necessary.
For example, I have read that at La Axarquia, local pilots start bitching when somebody comes and makes position reports in English.
Not my experience at LEAX either. As aart does, we usually use Spanish but at least some of the instructors and their students used English when we last visited a year ago and I’m pretty sure it wasn’t because of us.
It took me a while to get my head around the french rules about the use of English vs French language on the radio here in France, but for any newcomers, the following link from James Emery (bilingual ATC controller working at Bordeaux) summarises it nicely:
All controllers covering a CTR or providing a Flight Information Service in France, speak good English, so it’s really only the uncontrolled airfields that are an issue. James’ summary makes it clear what is legally allowed, but that’s not to say that all french airfields that I have flown into always follow those rules.
There is no separate radio licence exam in France. Moreover, French PPL exams are different from the UK in that they do not have separate papers for each topic. Instead they have just 2 consolidated papers, within which the (tiny) “communications” section is all in French. The net result is that 95% of French PPLs that I have encountered have little or no understanding of the English language. Hence, the proliferation of airfields that declare “FR Seulement” in the AIP and on their Visual Approach Charts. Therefore, for a non-French-speaking pilot, understanding what others are doing and integrating safely at uncontrolled airfields, especially those that are FR Seulement, is down to the pilot. That said, many French airfields have beautiful, long, tarmac runways, a decent café or restaurant on site or nearby, and very little traffic!
So, whilst the “rules” for the use of English in France are clear enough, I have no idea about the rules in Spain; nor to what degree the Spanish cover the use of English during their PPL training. Hopefull, however, Spanish PPLs understand enough English when those of us who do not speak Spanish, even badly, use the PTT button at uncontrolled airfields.
