I have a PhD, and have taught at your level. Others have made most of the important points already, so I can only add my backing.
I don't know what the dissertation timetable is on your course, but just to counter one or two other posts: don't stress too early. Your specific interests will develop with time, as will your understanding of your aptitudes and what's required from your dissertation. You don't need to start early, only on time. But if now is the time...
Research is a set of tools and techniques, independent of the subject matter. Of course choose a topic you're interested in, but the success of the dissertation depends on how well you formulate the question, gather the source material, assess it, and answer the question. This is more important that the actual subject, so pick something that will enable you to demonstrate your research skills. Detailed marking criteria should be available to you.
But, if you want the dissertation subject to help you get your first job (which it often will) choose something relevent. Do you want to teach kids?
Do statemented 10 yr olds have a longer attention span outdoors? Want to manage National Park events?
Do hands-on woodcraft activities attract more visitors? Want to lobby for outdoor access?
Bushcraft: pre-conceptions among landowners in northwest England. Those are rubbish titles, but you get the concept: you can probably fit your personal interest in bushcraft into a context that would be relevent to an employer.
Also choose something trendy if you can. Find out what's buzzing in education research at the moment. Do this by reading journals, and the TES, which will also help to inspire you in general. As a graduate, it's important for you to be able to demonstrate a grasp of the issues-of-the-moment within your industry.
Keep your question small and specific. This cannot be overemphasised. A full discussion of a small idea is far better than a limited discussion of a big idea. You need something where good data/source-material can be had, but not so much of it that you can't complete a full assessment of it all in the time and space available to you. Any researcher will tell you that the hard part is leaving stuff out, not finding new material to include. No matter how big your word-limit might seem to you now, you won't have a problem filling it.
Furthermore, a simple question will (hopefully) result in a relatively simple answer - or at least a simple story to tell. Simple does NOT mean dull or irrelevent! All professional researchers long for the simple. And if your story is simple, not only will it be easier to write, but it will be easier to read too, both of which will improve your mark.
Ask you Tutor's advice and take it. He should be getting to know you by now, and he's seen it all before. It is very easy to get carried away with enthusiasm and bite off more than it's necessary to chew. Allow your Tutor to temper your passion. Mine told me straight: "Hobbes my dear boy" he said, "first get qualified, then you can save the planet!"
I had a great time writing my undergrad dissertation - you'll enjoy it when it's going well. A passion for the subject helps with staying in the library 'til gone midnight. A simple question, easily manageable source-material, and the resulting sniff of a distinction, help with editing at four in the morning and printing with five minutes to go
Good luck!
