I suggest just using the dictionary to check the meanings, and picking up idiomatic expressions and vocabulary naturally by reading or listening regularly. I used to look for that kind of ESL material too, until I realized picking up expressions and vocabulary by practicing was much more natural and easy... and it gives the best results.
Personally I find a very useful method to be to get learners to watch English-language films, news reports, or even YouTube short-form video; get them to jot down words or expressions (more often than not colloquialisms) that they don't understand, and then just Google them. It takes a little time but the explanation, having been researched, tends to stick better. Plus, having seen the expression