Family Christmas dilemma

My DH told me today that he wants to surprise his family in Wales by turning up to Christmas dinner unannounced. We haven’t booked an hotel nor have we bought presents. We live in Kent so it’s a major trip. I have an issue with balance which causes problems with travel sickness and extreme fatigue. We visited in April so the journey can be done but with consequences. I think it unwise to just ‘turn up’ , he says ‘They’re always asking when are we going to visit again’. AIBU not agreeing with him? I don’t want to feel that we are imposing on the family at what is for a lot of people a very stressful time. Any thoughts, my fellow GNers?