In my honest opinion it will be hard for them at that age to settle into a state school, especially the 14 year old. Imagine at that age when they have good friends and are studying for their qualifications to up sticks and go to a new country where they dont speak the language, where the kids learn a different curriculum, and just be plonked in a room with the other kids.
Best case scenario is that the 14 year old will be put in a class with 11 or 12 year olds because of the difficulties. Worst case if that your kid fails all his/her exams and is completely miserable.
Both are (IMHO) too old to be dropped into state schools but certainly the 14YO. For him/her you will really need to get them into an international english private school to make the changeover at least more seamless because they follow the UK system.
It would be HELL on earth for a 14 year old and really screw up their future I can almost guarantee it in a state school - Even the "English Language" teachers often speak very poor English - I know, my OH's cousin is an English teacher and I am teaching HER english - its shocking (I would never criticise a Spanish for their English but she is a ruddy teacher in the subject FFS!)
Sorry to be blunt but obviously you need to know how it really is before you come!
As for your earlier post about work…. I can give you the phone numbers of probably 10-, 20, or 50 (with a little research) plasterers, buiders, "turn my hand to anything" people who are English, in the ALC region and on the brink of going bust… I am not saying dont come, but please spend time here, network, meet people and build the foundations before you make the move…
In Spain if someone wants a plumber (or anyone for anything) they almost never so what we do in the UK and grab a phone book or go on the internet, they ask people who they recommend… evryone (spanish people and established brits) know someone for anything, or someone who knows someone and THAT is how business happens here, so if you are the new kid on the block its hard - get known here, get your name out there and get contacts before you move… PLEASE… PLEASE… really PPPLLLEEEAAASSSEEE!