Hi Alexis. I believe English is the official language of Singapore, so I wouldn't think their English program would necessarily be geared towards English as a second language, but I'm not sure.
As for grammar recommendations, Eric, as you know, is a grammar lover (he gets it naturally, as his mom's undergrad degree is in linguistics
), so I don't know if these suggestions will help you any, but here are a few books we've enjoyed:
Nitty Gritty Grammar (and More Nitty Gritty Grammar) by Edith H. Fine and Judith P. Josephson
Eats, Shoots, and Leaves by Lynne Truss
Painless Grammar by Rebecca Elliott
For schoolwork, we tend to towards less is more. There is a very no-frills book we use, for about 5 minutes every other day, doing one page each time, called "Daily Guided Teaching and Review" by Wanda C. Phillips. We got it from Rainbow Resource. Instead of having Eric write anything down, we just sit together for a few minutes and do the pages out loud, with Eric telling me where he'd put commas, or what that part of speech a word is, or how to capitalize something. Even for a grammar lover, it's sort of boring to sit down and rewrite sentences with proper grammar.
Hope this helps!