Travelling when 36 weeks pregnant?!

Michelle • 31, married. 1 baby girl.
Hi Ladies. I just want a bit of advice/opinions please. 
Myself and my hubby live up North (UK) and each year we switch Christmas between family's, this year it's at his family home which is down South and a 5 hour car journey on a good day without stops. 
His mum is adamant we're going down and won't stop going on about it, his dad on the other hand is more on my side saying "we'll see" etc. 
When we're at their house I will be an hour away from the hospital (our own home in 15mins away) Do I seem unreasonable saying I don't want to go down?! I don't think she is seeing it from my point of view of being heavily pregnant and not wanting to be away from home incase I go into labour or anything. 
I have asked hubby if he things they would come up here if we don't go down but he didn't seem sure they would. 
What do you all think? Would you guys do such a long Journey? Or am I being unreasonable?
Thanks x