Definately a good idea.
The interval training (run/walk) buids your endurance and stamina. If you can run for 10 mins sometimes, I would probably say start at run eights mins and walk two mins, three times over, for 3 or four times a week. Two sessions in the gym and two outside.
Then go in to run 10 walk 2, then run 12 etc. Soon you should be able to run for 1/2 hour or more non-stop. Good luck, you are doing better than me already. I am only on run 3 walk one.
FP x