The fanfic you are looking for is the short and sweet A Bad Week at the Wizengamot by DisobedienceWriter.
- Harry gets expelled from Hogwarts and has his wand snapped:
…and this august body finds you, Harry Potter, guilty of misuse of underage magic. We expel you from Hogwarts and order your wand snapped. May you live a miserable life among the Muggles."
The Auror who was holding Harry's wand handed it to Cornelius Fudge. The small, plump wizard looked singularly pleased with himself as he'd just delivered the Wizengamot's 'justice.' With a look of glee, he snapped Harry's wand into two pieces. Many of the elderly witches and wizards were peering to the action in front of them. It wasn't every day a famous wand got snapped.
But instead of anger or tears or any strong negative emotion, Harry Potter stood up, nodded to his former Headmaster – who was frozen in his overstuffed chair and trying to calculate the damage this caused – and his former babysitter, Mrs. Figg, and then addressed the wizarding court.
"Sir, I have already lived a fairly miserable life among the muggles I'm related to. However, I would like to thank all of you for showing your true colors in this challenging situation. I realize how difficult it is to ignore the bribes you've all obviously accepted.
"I understand the fear mongering that Fudge is doing; his attempts at discrediting me so he doesn't have to think about Voldemort. The money that Lucius Malfoy is sprinkling around to get everyone to stop thinking. You've won this round.
"You've cleared up a number of problems for me – and created more than you can imagine for yourselves. I would like everyone here to know that I will be leaving Britain forever. With all the good and bad that that entails.
- Adult Harry, a staple of Indy!Harry fics:
"What threats are these? Have you finally cracked, old man?" Fudge was looking rather furious by now.
"Because you fools tried him as an adult, and subjected him to an adult's punishment, he's now legally and magically an adult…
- Goblins angry at Wizengamot:
"Big trouble, big…" Dirk Cresswell looked flushed, out of breath, and ready to cry.
Cornelius set down his cup. Dirk had always been a bit excitable this way. Pity if one of the chief goblins had a hang nail or some such nonsense. That's all the more severe it ever was with those surly little beasts.
"The goblins just lost ten percent of their assets and they're blaming you. More than one of them wants to roast you on an open flame and serve you up at a goblin feast…"
Cornelius frowned. How had he lost the goblins anything?
"Explain. Clearly, simply. You know I don't have a head for details or complicated explanations."
Dirk sighed and tried to calm himself down. "You forced Harry Potter to leave Britain. Well, he took his assets with him."
Cornelius considered this statement for more than a minute before he understood what his underling was hinting at. Then he began spluttering. "Ten percent of Gringotts? Belong to the Potters? Ridiculous. I'd have known a thing like that. I'd have made the boy an important campaign contributor if that were true…"
"It's true… They were wealthy enough when Harold Potter died, but then neither James nor Harry could do anything with the assets. So the goblins managed it… Twenty-eight percent returns per year, one of them bragged. The fortune increased by 1300 percent in twenty years… All their work, well compensated, but taken away from them. Because of you, they say…"
- Magical knight:
The sad part was that Harry Potter wasn't taking the Daily Prophet any longer, so he didn't see any of the results of Lord Voldemort's rather gruesome – and misplaced – peace offering. No, rather, the papers came out and announced that Harry Potter had just purchased a chateau in one of the wine producing regions of France and planned to produce under the label Chateau d'Chevalier Magie. The House of the Magical Knight.
- Fudge gets the flying guillotine:
You see, the toilet seat flew out of the ruins of the house with a speed and pitch that had it on a dead accurate trajectory for Cornelius Fudge's bulging neckline. It was also unfortunate that Cornelius had not been knocked down by the blast or had not chosen to run away from the situation. No, he had fully intended to watch the house burn to the ground. If anything, he was stunned into place when it exploded.
That was how it came to pass that Cornelius Fudge died that day when Dudley Dursley's oversized, triple steel reinforced toilet seat decapitated his rather pleased head from his rather battered body. Less than half the proper number of toes, no buttocks, and many other self-inflicted wounds.
Hope that helped!