I have a question regarding a multi dwelling property.

I bought a house as a homeowner, that has two apartments in the house, besides the main house.

I have rented out the apartments, but I have a room in the main house, and a roommate.
As well, I have all the utilities, heating, cable, electric, garbage, in my name.

I haven't rented out the main house out totally, and I can be there anytime.

Is there a legal amount of time, I must stay at the property to be legally considered owner occupied. I travel for work as well, so a lot of my work takes me elsewhere.

Do I have to change it to a full rental property?

You will need at the time the first renter is living there to notify your insurance copany since it changes the status to multi family or rooming house. And adds liability issues. With renters in the building, if the insurnace is not notified, they can deny claims if caused by them.

Very true - says so here (http://www.cheaphomeinsurance.co.uk)