Microsoft Office Installation

Hi! I'm a total dunce at techie stuff that isn't Apple! I've been using a Dell Inspiron N503 laptop, which I bought  in early 2011. I couldn't afford to buy Office at the time. I have been using Windows Live for my email. I've just bought Office 365 Home Premium. 

I tried to download it using the Product Key & was told that there were Beta versions of Office Click to Run on my laptop. I manually removed every single program that I could & yet I still can't load Office 

I have a feeling that Drive Q, which is a Dell installed Office Click-to-Run (2010) is the culprit. But I am told "Access Is Denied"... I'm at a loss as to what to do now! 

I desperately need to get Office up & running ASAP as I've started a new job. Everyone who is an "expert" with techie things has tried to help & still no joy! 

Please can someone help me out! 

Thanks, Sally