If you're wife does get the right to remain .and for example you move to Thailand then she will need it stamping every 2 years or she will loose it unless she gets an English passport ..
She will have to do hours of homework and needs to speak English . you will both be interviewed.when we did it it cost 1,500 pounds in 2007 it's very complicated we failed the first time ....so cost us double . good luck meticulous paperwork needed ...