I think for now you should save your money so you don't end up spending it twice. A ring flash can be had in your price range, but you are not likely to keep using it for very long. Bercause a ring flash will not get you more realistic lighting, it will do the opposite. It will wipe out shadows and create a very flat image.
Something like this gives much better results:
The advantage is that it will provide good illumination on your subject but without the off-putting flat looking ring flash images.
I use Nikon version called an r1c1 and had a ring flash before that. Big difference in quality.
If you want to look at options (due to price), graze through the list here (including several budget priced ring flashes):
If you are looking for wildlife photos (like birds and furry things) you will eventually want a longer lens. The Canon 100-400 is nice, although amongst lower priced lenses I prefer the Tamron 150-600 which is faster focusing and equally sharp and less expensive.
To use a flash with a long lens you will need a high power speedlite and a beemer. The beemer is really cheap but a high power flash to use with it is not. http/www.amazon.com/X-Tender-Better-Beamer-FX-3-Booster/dp/B000SLNNG4/ref=sr_1_1?s=electronics&ie=UTF8&qid=1463035817&sr=1-1&keywords=beemer+flash
For more general use, a Canon 580 II can be had used within your price range if you shop on ebay. Since you're talking £ not $, you might see what your local shops have. I haven't been in the UK in many years, but Jessops used to carry some used stuff as I recall. Does pixmania still ship to the UK? Their prices tend to be very aggressive.