I don't think they need classes anyway, the spouses can always teach them. My wife's English, although was good when I first met her, has improved significantly the more we talk. Even for someone who does not speak any English and has no background, even just teaching them "thank you", "please", "i'm lost", etc goes a long way. My parents, who were refugees from Vietnam 30 years ago, did not speak any English when they landed here, but after 3 years, they were able to converse pretty well, and they only have Grade 9 Education. Taking classes helps, but I think interacting with the community more and more will naturally improve any one's English.
My parents did tell me one important thing, and I agree with them based on my experiences with other immigrants. It's very easy for immigrants to hang out with their own communities and groups all the time, as it's comforting and familiar (ex. Chinese immigrants hanging out with other Chinese), but this is not a good thing in the long run, because you will become so dependent on them, that you will have a hard time adjusting to the rest of society, people should try to branch out to other communities. My dad said he always stayed near Vietnamese people when he landed, but he realized they weren't really helping him with his English, as they spoke Vietnamese all the time, and he wasn't able to learn more about Canadian culture and the way they do things through them, so he started to converse more with the people at work who had different ethnic backgrounds, and as a result, his English improved a lot in a short time, and he adjusted very well to Canada. And bear in mind, he has only Grade 9 Education and he worked as a janitor.