I think my horror film would likely be an independent feature, as the low budget quality and precise sub-genre would probably ensure it only reaches a niche (but passionate and dedicated) fan base. So i would need an independant complany to distribute it. After looking around the internet, i stumbled across "Brain damage films" (http://braindamagefilms.com/about/). This company specialise in distributing independent horror films, so that would be appropriate.
An example of one of their films.
But to try and get my film across to as many people as possible, I would show it in film festivals. In fact, there's a horror film festival in my home town of Nottingham (http://www.mayhemhorrorfest.co.uk/), so that would be a good place to go. My film would also get a release in specialised cinemas, and hopefully even some mainstream ones too.