There are various sorts of co-ops worker co-ops and customer co-ops. Basically it is about who owns a company. All these companies are still subject to market forces but it might make a little difference.
If you want to convert a company to a employee ownership or set up a workers' co-op then in Scotland the Co-operative Development Agency (previously the Employee Ownership Scotland) may help.
The supermarket co-op in Edinburgh is Scot Mid. It only costs a pound and means you own a bit of of them, see:
This is not to carpet bag them like building societies, which I am told is not as easy, as with them, but to support and direct community owned enterprises. One also gets some vouchers to use in the stores.
A separate Coop to Scotmid is the The Co-operative Group. It now has food stores in Edinburgh (those which used to be Sommerfield and some KwikSave before that) as well as many other parts of UK. You could see them as rivals to each other but they do co-operate and even stock some of same coop group products.
For co-ops on the net world wide see:
For a customer owned Phone and Internet provider use the:
For Energy try:
The Co-operative Bank merged with the Britannia Building Society so one can use their branches if you have an account with them, but due to bad commercial debt from Britannia they will be turning their bond holders in to shareholders i.e owners so no longer be a customer owned coop but a plc.