Blasting is less physical work. Sanding doesn't require specialist equipment. Both are be absolutely fine in preparing the hull, so whatever you can get a good deal on is fine. For the lead keel, due to the rough cast surface, blasting is probably better, followed by fairing with International "Watertite", then Interprotect. Although my hand labour with the drill wheel worked fine too and is still there, apart from a small spot on the front where we probably hit some UFO (just been diving down there cleaning it today). In hindsight, an angle grinder with flap disc would probably have been quicker.
Not much else to add that I haven't already put in those articles
Oh, I hope it's a lead keel. Iron keels are troublesome. In case of an iron keel I'd suggest watching SV Impavidus on Youtube (he's here too occasionally), I can't remember the details, but he's got a whole story about Coppercoat on an iron keel, along with all the problems they had and hopefully by now a solution for them!