OK so we are a long way from the "south east (Norfolk, Suffolk, Cambs)" that you want but I would like to support helicopter syndicates.
I am a member of a successful syndicate in HKG which has a target membership of twelve members, with an R22 and an R44. As the members are from different walks of life some fly mid week, most wish to fly at weekends, but availablity is a rare issue. The two different machines helps, as sometimes a member wants to fly three friends, sometimes just solo or with a partner.
We have got the costs down to a level that is sensible by world standards, especially when you consider that we pay 2.3 US$ a LITRE (yes, not US gall) for 100LL and depending on the exchange rate we are cheaper than private hire in the UK or Europe.
Like all groups/syndicates it is successful if the people work. So if you have a good one, be brutally honest about new members. Rather reduce the number of syndicate members and increase your costs than take on someone who might not suit all the other members.