How to tweak GREP to avoid specific characters after apostrophe?

Hi all. I’m presently using a GREP within a style to automatically put words in Title Case. Here’s the GREP:

Apply Style: UPPERCASE to text: \b[\u\l]

However this also puts characters immediately after an apostrophe (ie in the same word) in uppercase, for example UK’S and They’Re. Any way of creating an exemption within my GREP to keep characters immediately after an apostrophe in lower case?