As a retired airline pilot and having retired to Spain, I cannot but agree with most of the above.
If you are receiving a full airline pilot's salary, there is probably nowhere in the world where you will not be taxed at a very high rate. The tax in Spain is different to the UK but not much higher. As for the kids, if you are coming over here, do send them to a Spanish school. They will be fluent in Spanish in an embarrassingly short time and that will only be an extra qualification when they grow up.
On the personal side, I know of a pilot who works in Japan and his family lives here (month on, month off). It's a great place to live, not perfect by any means but the weather makes up for a lot.
It's late October and the temperature today, not excessive but a comfortable 25 degrees during the day and not a lot less at night.
Do think long and hard about it, but I highly recommend it!