Out of combat, you can use healing surges at will by taking a short rest. In combat, you need a special ability.
"Roll a d20 and add" was...well, earlier versions liked to use tables for stuff, and 4th Ed. doesn't have tables. It doesn't even have the random encounter tables that nobody used but everyone liked to look at, and that's a shame.
And yeah, I know, HP is not directly tied to health--except that it used to be. There used to be rules for healing HP gradually over a period of many days if you didn't have magical healing. Magical healing was omnipresent so it wasn't often used, yes, but if you were hurt, you were HURT. You might have been able to fight at full capacity yes, but you were indeed injured, not just shaken up a bit. It's silly to say that someone who has 80 max hp, and is only recovering 6 hp / day with non-strenuous bed rest, is simply regaining their wits and wincing at bruises for two weeks. Yeah maybe they don't have a broken arm, but it's not trivial injuries, that's for sure. In this version, there is literally *no such thing* as an injury which lasts for more than one day, the world simply has no concept of it.
...Oh yeah, speaking of bards, more of that crazy lack of verisimilitude stuff that makes it feel more like Erfworld. A Commander (or whatever the class was--the non-magical Leader class, like a military non-divine cleric) has abilities that make people run faster, or take extra (basic attack) swings. And that seems silly. If you have one big beefy fighter, and twenty level-one commanders, they can make the big beefy fighter take 21 swings per round at a guy. Back in 3.5th edition there was a myth that bards worked kind of like that, because one bard could give you a +1 to your rolls...except that they specifically didn't stack. No such restrictions with this guy.