Advice from mexicans living in the uk

Hi, I was hoping to get some advice from any Mexicans living in the UK. I am British, currently live in Mexico but will soon be returning to London, and am looking into the possibilities that my Mexican girlfriend comes with me, or comes in the future, to live in London. We would probably be looking at applying for a fiance visa, with the view to getting married later. Regarding work, she will be taking a Spanish teacher training course in Mexico to teach in England. She also has a child, who would be coming at a later date once everything is settled.
I would greatly appreciate any advice from others in a similar situation, hear any thoughts of Mexicans who have been through something similar, any links etc that could help.
Thanks!