I never once had a healer and I breezed through the game.
my party was me warrior, shale, alistair and morrigen.
All i needed were health pots and mana pots.
I don't see why people are so fussy about the healers.
On harder than easy or normal? I'm playing on the one above normal now for my second run, and to be brutally honest I couldn't manage without Morrigan having basic heal, and my own mage carrying it too.
I guess you did a bit of herbalism and created your own pots?