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.
Something to remember though you will be classed as a tax resident as you will have stayed in thailand for more than 180 days in the tax year January to December 2024
Definitely looks like the dates are wrong. If you hold a uk passport you can get 60 day visa exempt entry into Thailand and can extend for 30 days if you desire upto 90 days. So although there is an error in your visa you may not need one