I can have my real body protected for years as my Simulacrum lives my life. Something like The Flesh from Doctor Who.
Yes, but you'll probably want the clone spell instead
There's nothing in the way the spells work that stops this from happening. You create a simulacrum of yourself and then presumably someone else casts sequester on you, to which you are willing. This leaves a simulacrum of you free to do as you have commanded it. There are some significant ways in which a simulacrum is not you. It can't regain spell slots and have half your maximum hit points. It's a construct, so many forms of healing won't work. It can't learn or level up for you, and it won't make death saves when it's reduced to 0 HP but rather it will die instantly at that point.
So what can you do instead of using two 7th-level spells and 6500 gp? Well, fortunately for you there is a spell specifically for the thing you describe (or at least almost): clone. This 8th-level spell will only cost you 3000 gp (2000 of which is reusable) and leaves the full, actual you roaming around with a nice, fresh backup ready should something go... wrong.