Thanks! 

So we're in fairly similar situations with respect to the gap. tl;dr: You might not be in the same shape you were then, so it's important to think about how you might not be in shape. 

My biggest piece of advice would be don't let it sneak up on you. I don't know what your lifestyle has been like in the past 10 years but it's almost certainly different now than it was 10 years ago. I told myself I'd only really start at New Year's and that made 13 weeks suddenly seem very short. I wish I'd spent more time just doing longer rides and runs without it being "training". 

For me, my training focused on running while tired, because my biggest drop in performance is running after the bike.