Your work would certainly be good enough for an Art degree. It's really really nice. Are you sure you want to do a graphic design course? You won't get a lot of opportunity to do much work like what you have in your portfolio on a graphic design course.
I graduated a couple of years back, and we had a guy on our course that had an illustrative style similar to yours. By the end of the course, he didn't do too well because he didn't explore enough. Our lecturers would keep on at him to try something different, but he refused. He used this same illustrative style all the way through and found it very hard to translate that style into a simple business card or a logo.
I'd think about what sort of design degree you want to do, art or graphic.
For a graphic design degree you might need to show what you can do with simple things like typography, layout and composition, logos and digital. If you've done any work along these lines, post it up
Your work's very nice but probably isn't what tutors would expect you to be producing on a graphic design degree. Whilst you'll be expected to be creative and think differently about your approach, primarily you'd be working with typography and presenting information in a legible way.
Don't let that put you off though, good typography skills are very important, as typographical errors can ruin your work,. My tutors are also keen for students to explore other mediums rather than just going straight to the Mac for creating things. These are a couple of examples of the type of design work I've been producing on my design course.
I would say have a look at illustration degrees, these courses will teach you to use your skills in a commercial way but still having the chance to find your own style. Don't rule out graphic design but be prepaired to not be too precious about your ideas, this was something I was warned about before starting my GD training after being on a fine art degree, as fine art is very self involved.
I'll probably change it soon since I prefer clean, simple designs with a lot of white space and have a few ideas for a landing page/one page portfolio. Just need some better work to showcase first and I'm all set
Plus I feel a bit awkward referring to myself as a graphic designer in the title, since I'm always complaining about people who just give themselves the title when they have no real design knowledge, but it's mainly for SEO purposes (it would ne nice to get at least some ranking for 'graphic designer' for when I graduate) though to be honest my SEO is probably all over the place at the minute.
Referring to yourself as a graphic designer is better than some of those funny examples people gave. If you're using your name you need to have some sort of title that people can see at first glance.
I didn't like the idea of using my name, so came up with a name that went with a promotional mailer I designed and sent to local agencies introducing myself. Plus I use freelancers alot for web based stuff so a business name works better for that.
I took a 'Graphic Arts' course at Leeds Met which allowed for as much focus on Graphic Design as you liked or as much focus on Art and more experimental things as you like. I'd look into a course like that if I was you.