How can I fix Virtualization not being available in bootcamp windows?
Okay so I got it working with virtualbox with the help of VMWare. I tried AnonymousAppDev's answer but it didn't have any effect on my machine (at least not after the first reboot).

I read that VMWare may be able to turn on VT-x, so I installed VMWare workstation. That in turn asked me to remove Hyper-v since there's a conflict. After rebooting securable now says I have VT-x enabled and I'm able to run Virtualbox.