This all depends on several factors:

1. Weight of the plane

This is the total weight, including the motor, ESC, battery pack, fuselage, servos, receiver, everything.

2. Flying style

This means how you fly the plane. Electrics really require throttle management and discipline. If you push the throttle to full power and leave it there, you may get 5 minutes out of it, you may not. It's important for your instructor to teach you to fly and not using the throttle as an on-off switch.

You already described the battery pack you wish to use.

However, I suggest you take a look at the thread linked below, work your way to the bottom of the posts to the one about powering electrics, and work out the numbers. We could do it for you, but you can get the best benefit if you do it yourself.

http://www.rcuniverse.com/forum/m_10386274/tm.htm

CGr.