"I would be googling restraining order not marriage! " this!
Way too much, too intense, too soon!
10 weeks! You barely know each other!
And frankly as a csa survivor his interest in meeting your DC is ringing MAJOR alarm bells!
At best he think ingratiating himself with your kids will hook you into him more.
When is he seeing HIS kids if he's seeing you so much and going on weekends away etc? Is he even allowed to see his kids?
"and I’ve been present when they’ve called....they are adults...." That proves nothing could be anyone calling, hell in this day and age entirely possible this is an app set up or something.
"and the last relationship ended quite badly" exactly what did he say?
"He said he just wants to be part of a family....wants to fee part of something bigger.....his DC are scattered across the world so he doesn’t get to see them much....but my kids aren’t his nor will they ever be...." So he's not really got a family of his own and is trying to buy yours?! WHY are his kids so far away from him? That's a possible cause for concern too. Or is he lying about this so when you're at the point of introducing each other to kids it's easy for him to say meeting his is "too difficult" ?
"He said he realises that he’s been way over the top with it all and he allowed his romantic notions to take over....he said he doesn’t want to marry me anytime soon because we need to get to know one another properly....is keen to properly meet my DC when the time is right and is willing to be patient" he knows you're one step away from dumping and why so is saying what you want to hear.
"Don’t narcs have no awareness of their bad actions?" No they have awareness that people don't like their bad actions, they just don't agree that the actions are bad. They're master manipulators, the ultimate con artists.
At the very least I'd advise Clare's law AND Sarah's law checks on this guy.
DO NOT let him near your kids, frankly it's worrying he felt remotely ok just turning up to your home that way!!