Aim for 120+, or so, and unite the surplus in the autumn. Not much honey crop, if any, to be taken, so loads of feed can be provided all summer, as necessary, to keep the colonies expanding.
Feed and bought-in queens might be on a par, in cost, with packages. Depends on the season, I suppose.
My reply is: quite easily possible, but expensive, and needs a plan to follow from square one.
Would still likely need extra nucs, anyway, to take through the winter, to replace dud colonies over the winter period.
Several years ago, William (some will remember him) expanded at a great rate but failed miserably (due to poor standards, presumably) when disease got into his stocks. That was despite his mother setying him up, I believe.
Some beekeepers may never become proper/proficient beekeepers.
Manchester is probably as far north as sensible for this rate of expansion. I expect ITLD would manage far greater expansion - but not from his current stocks only. He would import a few pallets of package bees and be done with it, I expect.