Telescope advice for a keen astronomer?

I have a telescope but it's pretty rubbish (difficult to maneuver and is poorly magnified). I want to get new one that is actually good. Could someone please let me know roughly how much an actual decent telescope would cost, what brands are good, where to get them from and any other advice you can think of, I live in the UK. I'm a keen physicist and would like to get more into astronomy. Thanks in advance :)