ok, well the first thing to note about digital SLR's are the interchangeable lenses.
so you can buy the camera body, then buy 1 or many lenses to go with it, each lens basically specialising in something.
however, lenses can get very expensive!
a lens can easily cost more than the camera body.
i don't think you will get much for less than £300, so you may have to look on ebay.
for example, i think a canon 40D and standard kit lens goes for around £250.
when you have more money, you can then buy more lenses for it