Hi,
Your stall warner will sound before a full stall develops.(otherwise it would be a stall announcer rather than warner!)
As they would probably have told you you need increased back pressure in the turn to keep the aircraft level, this in turn increases the wing loading and this increases your stall speed.
So basically you will stall at a higher speed when you are in a turn. A good rule of thumb is you need 1 knot more airspeed for every 2 degrees of extra bank.
The Tomahawk may fly very close to the stall in steep turns, too long ago for me to remember but ask your instructor for a thorough de brief on what happened and make sure they brief you thoroughly before you fly so you know exactly what you will be doing and what to expect. You'll learn much more and much quicker!
Enjoy the rest of the PPL.
PS Unless its specific to the Tomahawk it shouldn't make any difference whether you are turning left or right.
