I have used (as a starting point) this site:
A Catalogue of UK AirfieldsOK, it hasn't got all the info needed for SkyAngel, but (in my humble opinion

) is a better starting point than what's on FlightNav.
I have spent many happy hours checking this data against Pooley and it was pretty impressive.
At least this way, you have all the airfields, even if few (quite a few to start with) would have incomplete info.
Instead of the situation now, where really active airfields "do not exist" because nobody bothered to put the info on FlightNav webpage and some farmer's strip with one movement every six

month shows up because the owner of it cared to put the info on FlightNav webpage.
Even this page:
Aerial Views of UK airports & Airfields has more complete list of airfields than FlightNav ...
I understand the problem you have in getting good reliable data, an I appreciate the attempt to solve it, but FlightNav will have to be a lot better than what it is now before I would rely on them