I've not had occasion to check the NPPL medical, but the old "pink chit" that was used for microlight medicals had no problem with colour blindness, except that you were prohibited from using an airfield where colour signals are the main means of communication with an aircraft. Since there probably aren't any, that was really no restriction at-all. I assume that if the NPPL medical changed that, we'd have heard the shouting by now.
By the way, I've just realised that nobody answered cessnasey's second question. Yes flying can get a lot cheaper after you've got your licence - but it depends upon how you play it.
For example, typical costs might work something like this:-
- Cost of dual: £120/hr
- Cost to rent same aeroplane solo: £100/hr
- Cost to fly same aeroplane in syndicate: £50/hr
- Cost to fly microlight or PFA homebuilt: £30/hr
But, to buy a microlight or syndicate share is likely to be upwards of £2k (there's no real upper limit). Personally, I think that investment is well worthwhile.
G