A visa for Spain, France, when married with paperwork to a British national for up to 3 weeks entry?

Yes, they will need to get a Schengen Visa. Having said that there is a rule about freedom of movement for EEA Family members but its recommended you get the Visa in case you have issues at the border or boarding the plane as they don't always adhere to it.

You dont say if your living in the UK or Thailand. Either way you will need to apply at the Embassy to the country that you will be spending the most time in and the same visa will do for both, that's presuming your going to France & Spain on the same trip.

There are a few threads on here if you search for Schengen Visa or do a search on google lots of info that may help.

My wife has had a couple of Visa's and its fairly straight forward to apply in the UK.

Andy

Strictly speaking, if she is traveling with or to join you then all she has to do is prove to immigration at her point of entry to the Schengen area that she is your wife and she is traveling with you.

But this will cause delay whilst immigration check everything.

More importantly, when checking in to travel, the airline may very well not be aware of the regulations and so refuse to carry her because she does not have a visa.

Therefore I would recommend obtaining a Schengen visa from either the French or Spanish embassy as described above. Read the form carefully, most of the requirements wont apply and the visa will be free. She must apply in the country where she is normally resident.

All the above assumes that she is traveling with or to join you. If she is not then the freedom of movement rules wont apply and she will have to meet all the requirements for the visa and pay for it.

If you are travelling to more than one Schengen visa country then the application for the visa should be made to the country where you will spend the most time, i.e. the main destination, at least that's what we were told when my wife applied about 5 years ago.