As PP has said, simply asking where your deposit is held might be all that's required in respect of that problem. (The landlord should have told you but genuine oversights do occur):
https://www.gov.uk/tenancy-deposit-protection/information-landlords-must-give-tenants
Unless you live in a 'house in multiple occupation' (where you share facilities, such as a kitchen or bathroom, with others), it's always your responsibility to pay Council Tax. The landlord is only required to pay Council Tax for HMOs.
http://www.landlords.org.uk/news-campaigns/news/council-tax
So you need to start by working out who should have been paying (and who remains responsible for paying) Council Tax to the local authority.