I've been in your situation twice. It's not easy.
If you've made up your mind, don't go back on it.
It's going to be really tough, no point pretending it's not.
My advice would be to go to a semi public place, like a quiet corner in a pub, or a quiet restaurant (I broke it off with him in Milanos....maybe should have gone quieter than that). Doing it at home can lead to more dramatics, and also means the conversation doesn't necessarily have an "end" if you know what I mean.
Tell him exactly how you feel. Tell him you still care about him, but don't want to be in a relationship with him any more. Make sure you are not ambiguous and that he knows that this is a break-up, not a break. If he keeps asking what he can do, saying he can change, you have to keep telling him this is about you and what you want, and nothing he can do can change that. You have to be clear.
Going home then is awkward. Both times for me, I had to stay living with them for a few weeks until things got sorted, but if you have your parents to go home to, great! If you can go straight home to your parents after the conversation, even better.
Then go back to the house maybe 2 days later. Don't go when he's not there, as that's really clandestine and hurtful. Maybe pack your stuff when he's not there, but stick around to see him when he comes in from work and say a final goodbye.
Due to living together, you will need to stay in touch over practical things, so try to do this in a considerate manner. Remember while you are trying to sort out the logistics, his heart will be breaking so he may be a lot more bitter and nasty that he really is. Just bite your tongue and try to take this (although obviously if he gets abusive get the hell away).
Offer him a month's rent for notice as you would with anyone other rental agreement, even 6 weeks maybe to give him 2 weeks to think before he has to hand in notice or whatever. He has the option of getting someone else in, taking the rent over himself, or moving out. If he decides to stay, then get the bills transferred into his name, if he decides to go, just cut them off as you would normally. Obviously tell him you will pay all bills due for the month you won't be there.
When all this is sorted, it's up to you both to decide whether or not you want to stay friends. Things can get very nasty in this first month, but I promise you it gets much much easier, and if you know it's what you want 100% don't let yourself be swayed by guilt in any way.
Onwards and upwards