You have really done a great job of imagination on this timeline.
I know I am coming several years after your main initial work, but if I may just make a few friendly criticisms, I would point to some contradictions or unrealistic choices, things I would have advised you to do differently.
First of all 1809. You can't realistically have Austria attack France alone on the continent.
If Austria attacked in 1809 of our real TL, it was because more than 250,000 french troops were mobilized in Spain. If you have no spanish quagmire to drain a big chunk of the french manpower, then Austria needs a continental ally.
For such an ally, I would choose Russia who was de facto at war against the polish french allies in 1809 rather than against its theoritical austrian enemies.
This would make a much bigger continental campaign and you could so have a greater Poland restored at the expense of Russia and Austria (Galicia).
Then the peace of 1813. What are the consequences for the UK being invaded ?
Almost none. No lastable change. In fact, the peace you imagined is much closer to a peace among 2 undefeated enemies than to a peace where one of the enemies has been totally defeated.
If the UK was defeated the way you described, it would lose a good part of its empire.
The City and the Crown would face an enormous bankrupcy.
There would probably be an uprising in India.
The french would probably get back Québec as wall as the dutch colonies, and probably not leave Brazil to such a weak Portugal.