don't just stop paying the sky, you will be contracted in - just ring up and try and cancel the contract, don't be sucked in by any "deals".
Can you maybe sign on wiht some other agencies for the supply work - my friend did supply and was on with more than one agency - it will pick up soon, i know this time of year is slack for supply teachers.
Do a "go compare" for things like house insurance and make sure you are paying the lowest possible payments, the same for car insurance - you would be surprised how much money you can save. look for better deals on your phone and internet - what about your mobile phone costs, can they be cut at all? Gas and electric can be put onto card metres, we have this and would never go back to bills, it costs about £15 year more but it works out much less because it forces us to budget with it and we never get big bills we can't pay.
Its horrible when things are tight, i know how you feel - there are lots of ways to cut costs before you start to feel the pinch just by shopping around, have a look on martins money saving website.
As for council tax, they will be understanding, if you talk to them, if you don't keep them in the loop they can be pretty unflexible.
We don't have anything on direct debit because if we don't have the money in we get charged (DP is self employed and has erratic paydays) whereas companies will generally wait a few days to a week for payments if you talk to them and let them know when you will be able to pay.