Cong back to the OP
My basic idea is Henry VII funds the columbus exploration in order to monopolize wool, eastern trade and cod fishing which leads to the Stuarts starting an immense empire.
Not sure why wool would be a big deal in the New World, but certainly England would be in a good position to leverage that. Cod fishing, no, England had lots of fishing much nearer to hand , for the next hundred years or so. Eastern trade ? Have to go round Cape Horn for that, not going to happen.
But, immense Stuart Empire. Like that.
To get an immense Stuart empire, the early English navigators have to go further south than Cabot. Set off westward from Spain, and, with a LOT of luck, the prevailing trade winds will blow you southward and westward, into the Caribbean. Columbus wasn't actually much of a navigator, a tree trunk would likely have ended up in the same place. But, set off from England, and the prevailing winds will blow you north and east. No good, until you are out of head winds, and then you're so far north that all you will find is ice. And those damn fish.
So, *Cabot, or *Columbus needs to go South, A long way south.
So, maybe
*Columbus gets disillusioned with being brushed off in Spain. Decides to try England, which had some reputation as a seafaring land.
Wanders down to the docks in Bristol (London would probably work). Gets drunk (as you do) , talks to other drunken seamen.
Now, the English sailors of the day did actually know a fair bit about what things were like out in the Western Ocean. Basically , to sum up in one word, 'crap'. They knew about Greenland (and Iceland) because of the whale fishery (quite big thing in England). And some knew, or at least had heard, that there was yet more ice and desolate uselessness west of Greenland. Nothing there except ice, shipwreck, savages and death. Oh, and fish.
So, Columbus gets one of those brainwaves that happen when a bunch of drunken people are talking.
"Go west from here , and all you find is ice. And fish. Thash no good. King wantsh gold. N spices. But the Portuguese , they got to India. They had to go WAY south. Kept going a little bit south , n trying to go east, ran into wasteland. Had to go way way south. I reckon (pause to refill), where whash I, of yeah I reckon, that there's a honkin big ocean way down south, goes right the way round the world. The Portuguese, they went south got to that ocean, turned east , got round the wastelands. I reckon , I reckon, that if I go way south too, and then turn west, instead of east, I'll end up in the Indies too. N get all the gold, n spice, n stuff, that the King wants. N get rich. Eastern maidens, too, get laid n all".
Of course, everyone being well drunk by now, they all agree. Wonderful idea.
*Cabot or *Columbus heads off to the King as soon as his hangover abates. King thinks it sounds vaguely sensible, and anyway , sailormen are dispensable and cheap. Go for it.
SO *Cabot/*Columbus sails south. If he sails as far south as the Cape of Good Hope, then turns west , he'll (without trying) pick up the south easterly trade winds that will blow him north and west, straight to either Brazil/Venezuela , or the Caribbean.
Getting back, he's in the hands of God. If he keeps heading north he can pick up the prevailing westerlies (the same ones that are problematic if setting out from England and trying to go due west). If he tries to go back the way he came, well, good luck with that.But if he makes it, King Henry may be well pleased. And a whole bunch of English seafarers will be fitting out ships as fast as they can.
Great empires have been founded before now on less.