sheer another hand - and more good tales from the other side.
I'm 42 and my 20 day old son is downstairs snoozing while DH plays trains with 2yo DD. I have a precious 90 min lie in with no child, but worth not sleeping to tell you all the good stuff.
firstly the 40+ fab mums to be thread is just that - fantastic. It saved me in early weeks when I had a lit on at work felt suck as a dog and was worrying about fact I had bled heavily a few weeks before I found was pg. I've just "graduated" to the 49+ mums thread set up because there were so many if us in our 40s. Three PPs are in it and have mentioned it. You will get kits of friendship, laughs and support from MNetters with un/planned pgs, delighted/terrified dps, and great baking in the coffee lounge we set up, where the rota if waiters and foot masseurs includes George Clooney, Colin Firth and Michael Fassbender 
second lots if us have had extra scans, mostly done by or linked to the Feotal Medicine Centre in London. These cost up to c £300 (but I think less too) and give you a massively more accurate early scan and estimate if Rusk numbers. Ladies on the thread above can advise you where or how to find out about it if you are nit in London (I am so went to FMC itself). If you an possibly afford it it is massively with it for reassurance.
Finally my DCs were planned (though DH did panic anyway!). But it takes 2 to make an accident, so to speak, so while it will help to share your fears and anxieties with DH you do not need to feel you take the blame or carry any burden if guilt for him. He sounds lovely though.
My aunt found our many years ago she was an "accident", and was v upset. My grandfather told her they had planned to only have 2 DCs but she was a live child. I have always been very struck by this lovely story.
Good luck, and I hope you and family stay safe and perhaps to meet again on the 40+ mums thread one day xx