Long and the short of it, myself and my partner are about to embark on a city break abroad which led me to this question. We both live in communal houses with little(no) time with the place to ourselves for mess. Hence in a hotel room seems perfect. I wondered if anyone had any experience prepping for a session abroad and if anyone has travelled with gunge powder in hand luggage? Worried about the security folks giving me weird looks for having powder in my bag!

I've never taken it in hand luggage and would strongly advise against it! I've had JLube in hold baggage but wouldn't even consider taking anything like that through security.

Either post it to the hotel or order it to be delivered to the hotel, and let the hotel know that you'll be expecting a delivery in advance.