Yes it's a well known concern in DAO, especially on higher difficulty settings. The best way I found to deal with that problem was to buy tons of ingredients and use the herbalism skill to create potions as if my life depended on it, and well, it does depend on it in-game that's for sure, especially with a warrior class character.
Another way I found was to use a "No Automatic Levels" mod for me and my party members, so that I could give both Wynn and Morrigan tons of points in Willpower and Magic attributes, get them the healer-related skills I wanted, find them mana-regeneration equipment, have them on my party at all times and basically have one of them spam healing spells for me and the team.
It's "cheap", but it gets the job done way better than having to rely on raw Elf Roots during combat for healing purposes due to lack of better alternatives. Additionally, equipment that grants extra healing effects received is of utmost importance especially for warriors (Sten, Ogren, Alistair and to some extent even Zevran and Leliana).
