miep There are several examples of writers who were successful in later life: Frank McCourt (Angela's Ashes -66), George Elliot (Middlemarch - 52), Anna Sewell (Black Beauty - 57), Mary Wesley (The Camomile Lawn - 70). I think PD James was in her 40's when she wrote her first book, and she continued to write into her 90's.
I know an award-winning writer of teenage books. She started writing while still employed full-time in a job she enjoyed. She wasn't writing because she hated her day job or primarily to get published/make more money but because she felt a real need to tell stories. If you have always wanted to write, now have the time and a real drive to do so, then go for it. What have you got to lose?
I'm not a huge fan of Stephen King - though I rather liked 11.22.63 - but I very much enjoyed his book "On Writing". It had mixed reviews when published but I thought it contained some very useful advice and insights.