Hopefully i can help..
Certainly sounds like from your description the clutch assembly/pressure plate or release bearing has failed/collapsed -."whirring noise" as you mention - hence too the reason you can't select gears with the engine running since the clutch disc isnt clearing enough to allow you to select gears smoothly..aswell as the juddering when you do get into gear would suggest the clutch assembly is faulty..sadly the next step really would be gearbox removal to make further checks on this as per the clutch assembly itself..but you should also make careful inspection of the clutch release system just to be sure thats ok..but going by your description its certainly looking like the clutch assembly needs replaced..I do hope this helps
Thanks for your help. Will try and have a look and hopefully a full clutch replacement will do it.
Hi..there Paul .. thanks for your reply..
Glad to help..However if you need to ask anything else then just continue if need be..Also please dont forget to rate my assistance much appreciated regards Robert