Crossing A1 to turn right into Wittering. (A1 heading South after Stamford).
Make sure that you can fit your vehicle in the gap in the central reservation.
Do not let the pressure build up, reassess the situation all the time.
Reset the clock, by this I mean if you have been waiting 2 minutes to cross, imagine you have only just arrived. You need to go when it is safe, you cannot speed this process up.
Just because you have been waiting a long time does not mean that you are being hesitant.
When it is clear enough, go.
If you are not sure wait until you cannot see any cars on the carriageway.