I tried to add a response yesterday but SQL central wasn't responding well.
ICACLS was returning what I was seeing in the security properties window. I did find out what my problem was in add the NT Services account. I needed to change the Location to my local PC from my Server, then I was able to add the account.

however that didn't solve my problem as I was still getting the access denied error so I ended up changing the 'Log In As' in SQL Configuration Manager to my login account which is an administrator account. This at least allowed me to start the SQL Server and get some work done.

As a long term solution I am not sure if this is the right approach though. Should I be creating a Windows account specifically for signing into SQL Server? If so, what rights do I need to give it.

Thanks again for your help 
Steve