Hi Jazza,
I am very much agreement with the other comments posted so far and I'll go one step further -- don't expect a lot at any time during this upcoming opposition.
Mars is a small world twice-odd the diameter of the Moon and it is a very very long way away even at the best of times. Even at opposition this time when it is closest to the Earth, it is nearly as far as it can possibly be at an opposition. Not all oppositions of Mars are equal and they come and go in a 15-17 year cycle (and I know that can seem like almost forever to a youngster like you) due for the most part to Mars' somewhat elliptical orbit. If we catch up when it is furthest from the Sun we get a lousy (aphelic) opposition. When we catch up to Mars when it is at its closest to the Sun we get a good oppositon (perihelic).
http://www.photomeeting.de/mars03/main_l08e-e.htm
2003 was an especially special one -- the best in fact since 57,618BC and Mars was 25.5 arc-seconds diameter. This one is pretty cruddy by comparison and at best Mars will be about 14 arc-seconds across -- pretty tiny.
At the time of writing, it is getting bigger, and currently about 8 arc-seconds. At the time of writing it does not cross the meridian until 7.30am -- in daytime. Because Mars will be well in the northern part of the sky during this whole apparition it won't rise high in the sky and it will be an exceptional and rare night that the seeing will give a good view and you'll have to wait till it is at its highest point in the sky (crossing the meridian) to get the best of it. You won't be able to use as much magnification as you could when it is high in the sky and you'll probably be limited to about x270 on the best nights -- likely somewhat less in practice on more ordinary nights.
Realistically, you best views will occur in the two weeks either side of opposition, about midnight. You must be ultra patient at the eyepiece and wait for those odd-seconds when the seeing will click in to see a much detail. The easiest and darkes feature to see is Syrtis Major, the polar cap will probably be visible and you may also see some other low contrast markings hhere and there.
To get an idea of how it will really, really look in a 10" f/5 Dob, try here --
http://telescope-simulator.com/index...d=45&Itemid=57
input your 'scope details and an eyepiece and it does the rest for you.
Hoping this is of some help.
Best,
Les D
