Hi Georgie,
In regards to Control Panels and the operating system, it is referring to the operating system that the server is using that is hosting your website. The Control Panel is the software you would use in order to manage your website. For cPanel, yes this is a Linux-only web hosting control panel. You do not need Linux on your end, it simply means the server you are hosted on will be a Linux-based server.
To manage your website (for example, to create your website's design, content, etc), all you need is a computer that can access the cPanel control panel, Plesk control panel or the Windows DotNetPanel via a web browser. You can also use FTP which can be accessed via an FTP Client (for example,
FileZilla on Windows). If you don't know, FTP is a file transferring protocol (meaning "standard") that allows you to upload, download (and subsequently modify and reupload) files to a web server. FTP is available on all Windows- and Linux-based packages.
Windows DotNetPanel is available for Windows-based packages only, while Plesk is available for both Windows- and Linux-based packages. cPanel, however, is only available for Linux-based packages.
Plesk in my opinion is just as easy to use as cPanel.
Hope this helps.