Re: Concrete Ukemi
At our dojo we are expected to do rolls on concrete by the third or fourth test; I can now do all the rolls & breakfalls outside without undue trauma (the odd roll still reminds me if I'm not smooth enough, though!). The trick, if it could be called that, is to get very low, and go slowly. To get sore spots when you first try it is to be expected. Keep trying, but as Thomas says, not too much - get comfortable on a carpeted surface at home first, something harder than the mat but still more forgiving than concrete.
And watch those ankles! It wasn't until learning to breakfall "out there" that I really discovered how to position my ankles so they wouldn't get smacked