I am with twogirls!
I dont get this whole, 'last chance to have a weekend away' business! 
Surely the last few weeks before you are to become a parent should be spent enjoying the excitement and preperations for the birth of your first child.
As well as supporting each other,not flitting off on a lads break under the guise of,'last chance saloon'?
He's already a dad,and surely his responsibilities have begun and if Louisa is feeling anxious about him being away that close to the due date he should stay home.
A lot has been said about early arrivals, but aside from that its more the anxiety she will go through analysing every twinge/pain while he is away that really is unessary at that point in her pregnancy.
And whats so wrong about saying 'actually honey,NO, its not a good idea' its the birth of their first baby I remember being apprehensive and twitchy at that stage with my first.
I consider myself to be quite laid back generally, but somethings you cant compromise on just to be considered 'cool'! 
Lets face it, missing his 'last ever chance to ever go away with his BF just a long weekend away to amsterdam ever before he becomes a dad ever' is not the end of the world.
Missing the birth of his first born child would be hard to reconcile!