Travelling with elvanse

Hi! I was diagnosed with adhd last year privately through adhd360, and currently on 70mg elvanse.

I’m going on holiday with friends soon, and I don’t travel often. I assume as elvanse is a controlled drug, will I need something like a letter to allow it go through customs?

It wouldn’t be on my GP report as they’ve refused shared care. Sorry if it’s a silly question, I just really don’t want to get stopped at the airport, and be unmedicated my whole holiday.