What are the requirements and process for applying for a UK tourist visa for my girlfriend employed in Thailand?

I hope you can get the visa without any issues. Good luck.

I did about 8 photos of us together and no alcohol in the photos. Proof of conversations on line or WhatsApp. She has to have land or dependent ( child is good) as far as I can remember. Normally not more than 25 years as they look at the age thing. Don’t load it with to much information as the Indians who check it only have 15 minutes to look at it. Label it as well with coloured labels with what you have like photos and cohabitation. Also she will need money in her bank. As they want her to have money to return if she needed if things don’t work out

It's an online application with VFS Global. Go to the website and go through the requirements for a Visitor Visa taking careful note of each requirement then ensure that, with the application, you include something to meet every requirement. I did it all in a letter asking for the Visa to be issued where I addressed each requirement with a note see attachment 1, 2, 3, etc referring to the documents supporting the requirement.