Hey mate,
When I sat Flight Planning around this time last year you didn’t have to calculate those initial distances from major ports to the first waypoints. EG, ymml-CANTY on the H3. They would give them to you as part of the questions.
I found the 5 markers not to bad; all the Q's I got wrong were the 1-2 markers. (seemed to try and trick you more)
Use any short-cuts that you know, i found that it was close enough for the 5 mark questions, Probably need to be a little more accurate on the smaller questions.
Good luck!