UK Landlord Forum / Life

Hi looking for some advice.  My friends moved into a property of mine in 2009 we didn't draw or any agreement due to being friends.  They pay the rent on the same date every month.  Unfortunately my circumstances have changed and now need to move my family back into the property.  I have spoken to them and told them they need to vacate the property by April 2017.  They asked for this in writing so they could go and speak to the council.  So i drafted a letter.  Apparently according to the council it isn't the correct way.  Any help or advice would be greatly appreciated. 

Section 21.