There's 16 years between me and DH. We'd known each other for 8 years at work before we got together (he was married, no DC, divorced befo we got together). Tbh although I on he was my soulmate, his age did out me off for, ooh a couple of months before we started going out. But once I'd got over that we were engaged 3 months later, married a year to the day after that and have a beautiful 3.4 yo DS. We got married when I was 30 and he was 46.
I like the fact that he is his own man as the BF I went out with for 5 years before him was an immature twat manchild. He is loving, young in looks and outlook and a fantastic person. His parents also had a 15 year gap and DH was born when his dad was 51 (and went on to have 2 more DCs). Interestingly, I think his dad was definitely of the older generation I.e. he was a Yorkshire farmer born in 1910 And I don't think he ever really 'got' his DCs. My DH though is young at heart (and 51 isn't that old nowadays) and there isn't that generational gap between him that there would have been in the 60s/70s.
I regularly take the mickey out of him for his age (he loves prog rock!) and silly things like he went to his first gig (Led Zepplin) when my mum was pregnant with me, got married to his first wife when I 8 etc etc. but it never causes a problem - it's something for us to laugh about!
I do get sad sometimes looking at photographs of him in his 30s. I feel like I have missed out on those years with him (although obviously I couldnt have known him in that way then). Knowing what a lovely man he has grown into, I reckon I could have coped with any manchildishness he may have gone through then.
I also do get sad when I think it's very unlikely we'll get to our golden anniversary like my parents, but I live each day as it comes and love the life we have now. No point in worrying about it until it happens.
Good luck - just enjoy it!