Underwear???
You are asking for embarrassment. If you have an unscheduled night stop, you can hand wash your trolleys and socks in the hotel in the sink with a bit of soap or shampoo and dry them on the radiator ready for the next day. That’s what I do
I am amazed that any fight crew bother with yoghurt any more.
I have been going through UK security, (and Europe, the US, Caribbean, Mexico, India, Africa and Canada), for 18 years as a pilot and have not had the sort of problems you seem to have had.