Urgent advice needed about ending tenancy and notice period...(see below)

Question

we have been renting a house as part of a house share with a live in landlord for 8 months nows. We have no written tenancy agreement and were not told how much notice to give.

BAsically we are excluded occupiers.

We have had troubleiwth the landlord from day one: coming into our room when we arent there, giving other people in the house with the same nationality as them preferential treatment, stopping our laundry in mid-cycle etc..

We have now secured our own flat and we are moving on monday. We were planning on posting the keys through the door and just moving out. The deposit will cover the two weeks we have lived there this month with surplus.

Is this illegal? What action can the landlord take? Do we have to give notice?