Aerofoil,
What time scale are you working to here? Nothing wrong with your plan provided you can achieve your projected earnings and SAVINGS you mention! It took me five years to save for my ppl (between the ages of 12 - 17), but after that my account has always held a negative balance!
"The repayments on the loan would be easily affordable (£450/month). I live with the olds and have no other outgoings luckily".
I take it you have not yet discovered pubs, cars. etc!