A neighbour has been constantly making false accusations of noise from my flat, he has previously threatened me at my front door, he has now accused me of being extremely intoxicated and stumbling in the communal area, I in fact have a disability which affects my leg (I walk with a limp) which in the last few weeks has been made worse by having acute tendinitis. He has put this in writing to our landlord who wrote to me regarding anti social behaviour. How or can, I sue for slander/libel?

In order to sue him you retain an Attorney and present your proof at a hearing or trial. You can collect if you have somehow been damaged by his behavior.

If you haven't already, respond to the allegations in writing to the landlord.