How difficult is it to get my Thai girlfriend a visa to visit me in London?

Reverse question for resources. I work in the USA 5 months a year, live with my 44 year old Thai Girlfriend the remainder of the year in her Village with Family. DON'T WANT TO BE AWAY FROM HER WHILE IN USA. Applying for Finance Visa, but wait times to long. SHE Can show significant land holdings, income, house lease, new car in her name, for Tourist Visa. She has absolutely NO interest of remaining in the USA. Thanks in advance for the LEGITIMATE answers. Sad for those who won't post questions because of the vile humans that often give their 2 cents and hide behind their screens and post mean spirited responses they are to COWARDLY to say to your face (sad to I feel a need to say this given how often the hate occurs). Yes and spent hours on Google and Youtube looking for answers.