shared house, not turned out so well! Options

[sleepyrabbit]

Hi guys, got a bit of a dilemma and thought might get some good advice on here, hope you can help!
I bought a house with a friend about 3 1/2 years ago. I put in the deposit but we pay the mortgage between us and his girlfriend also shares with us.
This is where the problems began really, he met this girl online (before we bought the house) and within a week of us moving in she had come to visit and basically she had never moved out again.
All fine and well (OK not really but I won't bore you with the 101 things I dislike about living with this cuckoo) but it has now come to the stage where I am fed up with living in what has become a house full of their mess and would like to go alone.
I have enough money saved and equity to get my own place but I am not sure how my friend stands and I am not sure he could afford his own place yet.
I am thinking of moving on in about a years time, so plenty of notice for my friend, but not sure whether to tell them now (that I would like us to sell the house next year) or wait nearer the time.
Any ideas?
A lot of my friends have advised me that I don't owe them anything as they have been such bad housemates so should drop this bombshell when I am pretty much ready to get my own place but I don't want to have any kind of fall out that could jeopardise my friend agreeing to go our separate ways.
Am I am mug for giving them so much notice or should I broach this conversation now...
Cheers!

[Astron]

Did you ever throw a massive tantrum instead of silently cleaning after them?