As a uk passport holder you will get a 60 day visa exempt stamp as you arrive, this can be extended by 30 days at your local immigration for a cost of 1900baht.
Perhaps ask the thai embassy in London about a medical appointment? You could book an appointment for a 12 month health check at one of the hospitals, get confirmation of the booking and see if that qualifies you for the DTV, you can then chose where to do your cooking classes when in thailand
yes they need to get a tourist visa. Have a look at the uk government website for all the details. It's doable but quite a bit of paperwork and planning
just look at the airline you are planning to use and check the flights that are within the visa I.e can't apply earlier than 3 months in advance. Take a note of the flight number and then put that into your application. You can buy the ticket later
you can apply for a 60 day visitors visa on the evisa system in the uk as that is still available, but since the visa exempt stamp changed from 30 days to 60 days mid this year then there in little benefit in getting the visitor visa as they are now both 60 days, visa exempt is free and no effort where as the visitor visa takes effort and money.
Andrew there is no need to apply for a visa as a UK passport holder, you will get stamped in on a visa exemption which is good for 60days so this will cover your trip duration. Prior to July this year it only used to be a 30day visa exempt stamp so all good for you 👍
Andrew you can get a 60 day visa exempt stamp when you enter thailand with a uk passport. This is not a visa but a visa exemption. This visa exemption can be extended by 30 days at the local immigration office when you are in thailand at a cost of 1900 baht.