Inherited a weird situation as a brand new Lord. Please help!

[Jason Wear]

Basically to make a long story short and to make things as easy as possible without getting any legal entities involved, I have a tenant who vacated the property and left his girlfriend there to take over paying rent about 6 months ago. Previous owner used a property management company who was never informed about anything and has been no help at all. It was a huge pain just to get a copy of the lease and the security deposit transfered over to me. The guy is on a month to month now and his ex girlfriend wants to sign a year long lease, providing that she's qualified. I know a 30 day written notice to vacate is required by law but if he and I are both in agreement to end things right here and now is there anything stopping us from doing so? Is there any paperwork that I need to get involved to cover both of us without having to give a formal 30 days notice?