I have an "integrated masters" degree. How can I eventually gain a PhD? I graduated in the UK last year with an M Ost, an integrated masters of osteopathy. This is currently the standard qualification offered by colleges teaching osteopathy in the UK, although it's changed several times in the past and seems likely to change again.

My course consisted of 480 credits. 360 credits were at undergraduate level (including 120 at honours level) and a further 120 credits were at master's level.

I am intrigued by research, and wonder if it would be possible to eventually apply for a PhD, but I have no idea whether applicants with integrated masters courses are considered. I suspect not, and assume I would need to do some extra work.

However I don't understand what that extra work would be.

As you can tell.... I am a little lost! This seems the most basic of questions, but I am struggling to find any clear advice. I have contacted members of the faculty in my old college, but they haven't not been very helpful. Suggestions have included doing a further qualification in osteopathic studies -- something I'm not keen on. I would prefer something that is science-based, and would be accepted as qualification to go on to apply for a PhD.

I appreciate this is quite an open-ended question. Ideally I'm probably looking for pointers as to where and how to continue my search. Should I contact PhD-providing universities and colleges directly, and ask what I would need to do in order to be considered?

I also understand that PhDs are hard, hard work. I am not looking for questions around why I want to do one, or alternative options. Many thanks for understanding this.
In the UK, you will be expected to have some research experience before applying to a PhD programme in science: not necessarily publications (although that always helps!), but certainly having done an extended project and written a dissertation about it. In my field (physics) you can definitely apply straight out of an integrated masters degree, provided that your last year had a substantial research component. 

If you don't have any research background at all (or just short summer projects or the equivalent), then this is the "extra work" you are looking for. Find a MSc by research in a field as close as possible to the one you want to do a PhD in. This also has the advantage that you get to decide whether a PhD is really for you while only taking a year, and to leave with a qualification at the end if it's not.

Of course, this is just general advice: as JeffE says, individual universities will be able to provide specific information on their admissions and funding criteria.