Hello Bob and good luck!

I have a club-mate who is a native of Northern Spain (albeit north-west Spain as opposed to the Basque region), and he is always talking about the local races "back home".

I'm personally doing a race this summer in Spain (ok Tenerife!)

The race you're signed up for would just sneak into AL category for a fell race, based on amount of ascent per mile, so will certainly be a challenge. My advice would be to run your own race... if you feel the need to walk the uphills when those around you are running, then don't let it worry you.

I would expect cycling has given you a great base of fitness to carry into running, particularly on the hills/fells. But what will need developing is the resistance to the attrition of running (as the lost toenails and various issues highlight!)

I personally find that fell running helps me avoid some of the repetitive injuries that my clubmates seem to suffer from (a road/track/xc club), but injuries sustained on the hills seem to be more 'interesting'!