I've PU'd France as England a few times.
ALWAYS do it on the first war. Don't wait, don't weaken them, it serves no purpose. Also remember that the BI can still fire for France when they are PU'd under England meaning you get France and Burgundy. At that point you can give up on Europe for 100 years other than small wars with Provence, Brittany etc, focus on uniting your islands and colonising, then come back to Europe when you're filthy rich.
The strategy is simple. I've found this works best with one ally, no more. Why? You want France to get distracted by Aragon and not fight your men. The AI always picks the weakest target and if you have say Castile and Aragon as your allies, the AI realises there's no point fighting south, they'll fight north. So ideally just ally Aragon, send your men to northern France, hire a big merc company to scare the French, when the war fires, send one stack to Provence and one to Chartes. Peace out Provence then go for Paris.
After that, avoid battle (it's not too hard if France are still fighting Aragon) until you've gotten at least 3 of their forts. If you're able to win 1-2 battles from there you should have the warscore.
I should mention, France will ally Scotland maybe 20% of the time. If this happens I would restart. It's not impossible but it makes the war a real pain in the backside. Ideally, Scotland rivals Denmark and you can ally them preventing the French from allying them.
Indeed, the most difficult thing is now getting their relations to above 0 before your ruler dies.
One idea is to sit on France in the war until the War of the Roses fires. I find that inefficient. There's a lot of rng involved here but by giving the money, ending the War of the Roses asap, hiring an improve relations guy and declaring on an Irish minor, you should get them to above 0 within a couple of years.
Like I said, after that you're pretty much a beast. What I usually do from here is attack Castile as Castile/Portugal have zero chance against England/France/Austria (Austria will ally England 100% of the time) and even Burgundy under your PU. The reason I do that is if you can sufficiently wreck Castile/Portugal enough pre 1500, the Americas are 100% yours. You might end up with Friesland or some random nations trying to colonise but they're easily dealt with.