BBC iplayer

You must use the default browser to view iplayer and you tube - I get the same problem when i try to view the sites in opera, but they work fine in the default browser

If you havent installed another browser (like opera) then you are probably using the default one. You can check by going to settings->application settings->default application->browsing internet. If this is set to web you are using the default browser.
Were the iplayer and youtube apps preinstalled when you got the phone? Have you tried using them instead of using the browser to access the sites?

I cant find a way to disable (or in your case enable) flash in the browser. It just worked for me when i got the phone.
The only thing i can think of that might be causing the issue is you have an old firmware version (and hence an old browser version). Can you try connecting your phone to a pc, running ovi suite and selecting tools->software update from the top menu. The device software version should be 011.012, and if it isnt, it should give you an option to update. If it is up to date, you could try reinstalling it.
Before doing any software update (or reinstall) please make sure you back up all the data on the phone (this can be done through ovi suite). It should keep it intact, but it is always better to have a backup just in case.

Just had another thought about this. Are you trying to access these sites over a wifi connection or a 3g connection? Most uk operators block iplayer (and probably youtube) when connecting over a 3g connection. The only way to access them is via a wifi connection

Finally got there antxxxx!

I had to open the web browser, choose options, settings, general and enable Java/ECMAscript.  Thanks to the Nokia support team!  And thanks to you for your suggestions.