Re: North Weald's New Year Fly-In, this Sunday!
Published approaches in the UK, for the time being, require an ATCO with an Aerodrome Approach rating to control them. There would need to be a change in the law if approaches were to be permitted to uncontrolled or FISO-"controlled" fields. If this were to follow the American model, a local Radar-equipped approach facility would control the approach, handing to the FISO or A/G once the aircraft was passed the Final Approach Fix (or similar).
[Note there is an exception in the UK - certain of the HIAL airports accept commercial services on instrument approaches on a FISO-only basis. This is a one-off waiver.]