Personally I wouldn't suggest an airband radio. The cheap ones have mechanical tuning and it's impossible to know what frequency you're on let alone preselect one. A digital one where you can select the exact frequency is better but in most cases, unless you are near an airport or radio transmitter, or have a decent roof mounted aerial you'll only hear one sided transmissions from airborne aircraft.
At ground level, VHF radio range is extremely limited and without hearing two sided dialogue you're wasting your time.
Listening and learning radio calls in relation to what you are actually trying to do is much more important (taxi, take off, MATZ, radar services, flight information etc). A £20 airband radio is a waste of £20, a £150 one, a waste of £150 for what you are trying to achieve. Practise is the best teacher. Good luck with it all.