Sky demon is by far the best planning and navigation app for the iPad. It is about £180 initially including the Nav upgrade then about £80 a year subscription (you can sign up for a 30-day trial free). I have used air Nav pro for quite a long time and found it perfectly adequate for most VFR flying, granted it is not as intuative or polished as sky demon but it is MUCH cheaper! About £40 including the optional UK half mil chart.