Well done Hanniball only as you say, a big job, such a pity when the stables have it all.
Two inches of manure is good esp. when well rotted. It would be ideal if you can do all the beds, maybe one a week until November?! Keep you fit…
Then the same next autumn if possible, or a little less. It will repay for doing in easier weeding, and ultimately less weed growth, better moisture retention, bigger crops… keep all that in mind while humping sacks.
Not sure if cardboard is needed, since you cleared the weeds, though it won’t hurt to stop new weeds until next year.