1. The College of Knowledge does add "fare payers", when possible, to NATS courses. More than one "elderly" person has been seen mixing with the kids. Most often however they are usually shortly to retire military persons converting to civil (at their own expense). Having said that people with no previous have been known to pass through - usually successfully - let's face it, shelling out £6 - 7k of your own hard-earned tends to concentrate the mind a bit!
2. Joining a Dutch course is not on - it is carefully(?) designed for the Dutch and as such would not get you a British rating.
3. If you really want to do it - do it.