Health & Ski Insurance
For Europeans, the E111 is _not_ valid in Andorra.
You are not allowed on Arinsal ski-school slopes without health/ski insurance. However the fee for this should be covered in the tuition fees.
However the health care and hospital systems are absolutely excellent
Dont drive too early in Arinsal if possible. Every morning in winter, there are council trucks that clears the snow off the mountain roads. Otherwise make sure your car has excellent traction & brakes as Arinsal is built along a slope, so its not for the nervous/less confident driver.
Please check http://www.ospreyweb.pwp.blueyonder.co.uk/driveregs/andorra.htm if you plan on driving to Andorra - the link was too long in the website box, so I've put it here.