Another approach that would be worth looking at can be found here, http://fablabamersfoort.nl/en/page/fablab-instructable-0
While it’s specifically aimed at the FabLab side of things, it’s a good example of how a small group of people got a workshop together.
To paraphrase both Russ and Jonty, get the group of people together first, as it will be easier to get a tool-set organised when you have a group of people, but it is difficult to do things when you don’t have other people to share the cognitive baseload.
The people from Amersfoort had the group of people first, THEN, they got the FabLab built.
IIRC, there was a group of people who were going to try setting a hackspace/fablab/makerspace around Barking & Dagenham. This included Tom Hodder, Ben Blundell, and, (I think) Ian from Chelmsford hackspace.
I don’t know how far they got, but they may be able to help you.
Also, as a sidenote, Barking & Dagenham council, are having to make a lot of cuts to their services, as their budgets are being cut by 1/3rd over 5 years.
One of the approaches that they are using to try to fix this is to set up a makerspace/co-working space near Barking tube-station, along with a number of other community projects. More information can be found here, https://www.weareeveryone.org
This approach is being looked at by a lot of London Boroughs, including Havering & Redbridge. At one event i went to, there was someone from H&R council coming along to assess how it was going, with a view to trying this out themselves.
So your borough may be looking for someone to work on things over there, and, at the very least, you may be able to get the use of some cheap/free building-spaces for the first few years.
Try getting in touch with them for the medium-term, but i would concentrate on finding some people first.