I switched a few months ago, and I'm 32, so I was similarly concerned!
My best advice would be to just be honest about why you made the switch - in my experience people who ask really are curious about "why now?". I expected a lot of criticism but I have been quite lucky and most people are understanding - there's been a lot in the news this year about welfare in the dairy industry, and the environmental impact or meat-eating, and a lot of people have responded along the lines of "I'd love to, but steak/cheese".
I had to explain to people in my workplace who would otherwise expect me to eat cakes and other snacks, and to people who I'll be eating with. I'm also conscious of being preachy, and as I'm still unsure of how best to advocate I'm keen not to give people the wrong impression. I usually just say "I don't eat meat and dairy any more", which gives people the option to ask questions if they like. My pescetarian friends are particularly interested, and some of them clearly have a lot of guilt, so I talk to them about what I eat and how easy it is, while also reminding them that I have a lot of catching up to do, since I ate meat for so long.
I was also anxious about going out for meals, and I'd recommend phoning the restaurant in advance to put your mind at ease. Once you're in the restaurant it's sometimes good to approach a member of staff so that they have some options for you when you come to order, as this gives them time to figure out some options with the chef - it's quite awkward to start quizzing waiting staff on ingredients in front of a table of guests.
Trip advisor has added the ability to search for "vegan" within reviews, from the restaurant page, which has been super useful! This is a really quick way to see any issues that others have had.
I think Italian should be OK? Penne arrabiata, salad, olives, bread... Indian food I'm not so sure. I have the (perhaps incorrect) impression that everything is cooked in ghee, but others may have more useful advice on this. The good news is that it's getting so much easier. Stables (a UK pizza chain) and the lounges (nice UK pub chain) each have vegan menus now, and I've rarely failed to get a good meal when I've had the confidence to ask for one.
Anyway that's quite enough from me! Good luck with your friends and family - I hope they're kind and open minded, and I'm sure you'll find lots of lovely things to eat