At a primary school I used to run training sessions at they had a container with kids bikes in it. They'd get them out at lunch time and let the kids ride round an area of the playground seperated from the rest by car tyres. Just had a member of staff overseeing. Fair attrition rate on the bikes.
At another one we went in and did bike ability, then some staff and volunteer parents got trained as ride leaders and continued to take them out.
At the local posh secondary I did the bike ability and the head of games got trained as an MTB leader and took them mtbing. This was on the playing field and local park.
I would suggest looking at Go Ride (or whatever they are calling it this week). Also look to see if CUK are doing Community Cycle Clubs in your area and see if you can get support that way.
General cycling advice ( NOT technical ! )