Hi Rose,
Firstly, your gallery is superb.

I can see why you're wanting to do an A Level in it.
I have to be brutally honest and say that my experiences of high street stores has not been great, in terms of advice, price and range. Certainly in some stores (even specialist camera shops) you may find someone who knows nothing about DSLRs, but will wing it and try to sell you one. Others are very biased towards certain brands, or deals of the day. They are all very much guilty of trying to sell you want they have in stock, not what you want/need. Anyway, enough grumbling...
I bought my camera body from a high street store, but all lenses, accessories (in particular memory cards!) were bought online.The highstreet chains rip you off on a lot of the extras, and carry a VERY limited ranged of lenses etc. When you've decided on a package, we can advise you on the best places and prices if you can persuade your mother to buy online.
As others have said, for £1000 you've got a lot of options, so take your time. A DSLR+kit lens is a good starting point, but has limitations, which you may hit fairly quickly if you're studying photography formally. Before we talk brands and cameras, I'd like to suggest some lenses, as these will have more direct influence on your creativity than the body:
A safe choice is a 50mm f1.8 prime lens. These are usually very cheap (about £60 on Nikon/Canon), extremely sharp optically, and allow you to play around wonderfully with shallow depth of field. Because it's a fixed focal length (and quite long actually - a short portrait) it forces you look at the world in a particular way...it's FAR more fun than wandering around with a zoom.
Another prime lens that should be high on your list is a macro lens. These will cost you about £250 but are the best quality lenses you can buy, and open up a whole world of possibilities for cool photos (as you know, judging from your gallery). Like the 50mm f1.8, these macro lenses allow a lot of flexibility in depth of field, so you can create some wonderful effects, as well as opening up a whole new minature world. Macro lenses in the 90mm-105mm range are also very good at big subjects too - they are a superb long portrait lens.
Depending on your areas of interest, you might also want to look at a 10-20mm superwide zoom (£280), or a telephoto zoom up to 200mm or 300mm (roughly £150-£300). I might be corrected on this, but I reckon a superwide would be a lot more use for a photography course than a telephoto - for a start they need a lot of skill to use well, as you need to be very careful with your composition.
As Senu says, also budget for a tripod, a memory cards and possibly a spare battery and external flash...and a bag to put stuff in!
As for cameras...
If you're actually not planning on getting many lenses, the Nikon D40 would be a top pick for value (£290 with kit lens). The D40 doesn't autofocus with some popular good value lenses, so although it's great value at first, it could mean you have to buy more expensive lenses for it later. It's also very beginner friendly and very small and light.
Next up the price ladder are the Pentax K100D, Sony A100 and Canon 400D. Canon has the edge when it comes to lenses and accessories (and the prices of the lenses is often less), but Pentax and Sony have built in vibration reduction. This is a killer feature, as it makes ALL your lenses image stabilised, whereas Canon/Nikon make you pay for it on each lens. All three are about £370-£400 with kit lens.
I'd also seriously consider the Pentax K10D, which at £460 offers a more 'pro' feel camera at a bargain basement price. Like the Pentax K100D you get image stabilisation in the body.
£600 gets you a Nikon D80 or a Canon 30D. If you play with these, you'll find them very tempting, as they're both very nice bits of kit, but be aware that they'll not leave you as much for lenses.