how much notice

Possession - Section 8 and Section 21

I presume cos his tenancy expired in Jan he is now on "periodic notice" - in which case you need to give him two months notice - issue section 21 but make sure you issue on the right day - check the details.
With regard to his bills - SURELY he is paying his own elec and gas and council tax????? If he is then it is not your problem as long as the accounts are registered in his name. If the house is cold you are not necessarily to blame - tho there could be issues here with drafty windows, doors, bad insulation, whatever. Minefield.
At the end of he tenancy then you can use his deposit to pay outstanding rent. He MAY NOT use the deposit to "pay" rent.
good luck!