I'm posting info about Transition Finsbury Park events and news here They have got lots of good ideas. They also have a blog which you can find a link to in the posts in the environment group.
Hi yes, next project nearest to Harringay area is at the Jamboree Play Huts in Finsbury Park:
Sunday 7th March: 10-4 drop in - 'Learn to Build Railway Sleeper Planting Boxes' & followed by 'Learn to Plant Fruit & Veg beds for All' at Jamboree on Saturday 20th March 11-2.
Children are welcome to come along and play & I believe refreshments will be provided.
I went along with my partner and children to The Green Lanes planting - seems like the group is very driven with lots of ideas/ projects for the area.