if you get a date sorted and people from outside of london want to come if you go to
National Express // Funfares you can get coaches to london for £1. i would come but if i was sat for the full coach journey my back would sieze up and id struggle to walk if its a success though u will av to have one a little closer up north
Go in to your local train station when the date has been set and ask for the best price for the tickets. If you are ok with being restricted to certain time trains then you can get them pretty cheap.
I'm up for it, I can get to Paddington but I might struggle to find my way around from there!