General comments that I have heard many times in this area are "You can't make a profit teaching PPL's due to weather and costs" - "PPL training only covers costs due to subsidy from underpaid and overworked FI(R)'S who work ling and hard for a year or two and then move on hopefully before personal bancruptcy"
etc etc etc
I think that competition from USA, strenght of sterling against dollar and winter weather are all obstacles that you face
Good luck but look at your business plan and make sure that the numbers crunch OR that you have a wealthy backer who can afford to loose some tax money on his favourite pasttime.