There will be AR appointments for Cup matches, Prez XV matches, maybe some top schools matches in your Society, but it is limited usually.
If you are asking about the RFU AR Pathway, we have three Elite ARs (one of whom is an IRB AR) and two NPR ARs. So the Panel AR Pathway is well trodden by our members. There are limited AR opportunities in Society, unless a Services Match Official where more fixtures needing Teams of Three exist.
As Societies we do not have enough referees to cover the matches let alone provide Teams of Three. The changes proposed by the RFU ACR review could change Level 4 and Level 5 League structures in 2016-17 with many more matches requiring teams of three and expansion of ARs to Level 5 suggested by some - where are these suitably qualified ARs going to come from in 18 months time and can a minimum of L8 for AR2 and L6 for AR1 still be realistic - who will ref the L6-8 matches ?
All of the ARs above were and still are L6 referees in their own right, and do turn out at all levels for the Society as referees when their AR duties allow - this is rarely.
One of the NPR ARs got on the Panel last season after a three season effort to build up his AR resume, and at the same time continuing to impress at Level 6 as a referee. He travelled all over to take any AR opportunity and worked with RFU AR management and coaches to get his performance levels to required standards.
My personal experience and view (which may be wrong and may not be any form of RFU Policy or criteria) is that fewer ARs will come from the Society pathway, but come from retired NPR Referees, who AR while active referees anyway, and from ex-Group Level 5 referees who do not make selection to PNR Referee. Each season out of the 50 or so Group L5 refs maybe three or four make it onto Panel.