I recently got back into skateboarding after 15-20 years (I was terrible at it back then, my balance has actually gotten better since). Cruiser or a longboard sounds like the way to go. For me, the footpath and roads in my area are rough and terrible, and I probably should've gone a cruiser, but my heart was in a short board. I'll play around with different wheel configurations later on.
Best thing to do is go into City Beach, have a stand on a few boards and see what you're comfortable with.
My story's a little different. I recently landed my dream office job. I wear jeans and a t shirt to work Monday-Friday and they let me get my eyebrow repierced. I was planning on buying a bike, but a skateboard ended up being more me.
As for the age. This is Danny Lenihan, retired standup comedian and now CEO and founder of 3 Legged Thing (my favourite tripod brand, and photography brand in general), 43, and still skates shortboard like a mofo. You'll be fine. And if all else fails, fake it till you make it. https://www.instagram.com/p/BKGaGglgDQ7/
Also, I found this website to be a wealth of information when researching: https://www.warehouseskateboards.com/help/buying-guides