Depends on what her and your purposes are. She can come here first time for tourist visa or if she want to get a job, she need visa for working or you can find the agent who do MOU for working and ask them information. It might be easier for you. Please be careful if the Immigration caught. You might have to spend big money for working without work permit.
2 months it might be too much for tourist visa. She need to have money in her account to prove for your government even you said you would look after her. It is ot easy for this time now for us to visit UK. My friend got denying last month in the same reason and she need to show them like children, her job, or property she got and she need to come back Thailand. Lastly she need to buy travel insurance too.
You agent can give you more information for that. More staff more expenses I understand but for setting up the company and processing for work permit I think it is necessary.