LHR Clubhouse Guests

Hi early birds. Just a quick question. Myself and partner are flying UC to JFK today. We also have two friends flying in economy. I know we can guest a person each into the clubhouse but I've just had a sudden panic that I needed to do this in advance?
Can we just turn up at the Clubhouse or do I need to do anything else to get them access?
Thanks!

Morning (or evening from SF!)

You don't need to arrange in advance. Just speak to the lounge ladies at the entrance.

Have fun and a safe flight!