I agree with all the above comments. At High Wycombe/Booker, we used to plan the first track from (and last track to) the Stokenchurch mast. An easily-visible landmark and known to all students who used to leave the circuit to the north for general handling exercises.
Another method is to plan from the overhead. After departure, turn onto a heading that intercepts the track by 30 degrees. When the airfield is in your 5 o'clock or 7 o'clock, you remove the 30 degree intercept angle and you will be on track. This method may of course have to be modified to fit in with local departure procedures. Start timing when airborne, or for large changes of track, when abeam the airfield.