Gaming - I got a buget of £500 pounds where can I get a good monitor from to stream and game from ?

I guess you are in Great Britain, and that might be important. In the USA you can get good advice and good prices at www.tigerdirect.com or www.newegg.com but I don't know about dealers in other countries.

Here is a link with information about monitors: www.howtogeek.com/305410/hdmi-vs-displayport-vs-dvi-which-port-do-you-want-on-your-new-computer/