You're right. More specifically it's Cockney (east end of London) rhyming slang. Basic rule: find a phrase that rhymes with the word you mean, substitute the phrase, but leave out the rhyming word. So "butcher's" = "butcher's hook" = "look". So "take a butcher's" means "take a look".

I had a Cockney father-in-law, once upon a time, so a few phrases crept into my lexicon. I still use "don't chicken about it" = "chicken curry" = "worry", and a couple more.

You don't always leave out a word. Some of the more famous ones, that most English people have heard, are "trouble and strife" = "wife", and "apples and pears" = "stairs" - though I never heard anyone use those particular examples in regular speech, they're often given as examples / stereotypes / satires of the style.