How do I activate Windows 7 by phone, if I do not have the option?

[Solo123]

Not sure why, but every time I've tried to buy software from Newegg it always comes up as "unavailable for UK" when I'm in the cart.
Not sure if this is some sort of restriction on shipping to the UK? Anyone else had any luck with this?

Would you have to do a clean install with an OEM key for it to work, or can I just type in the key when prompted. Also do I need a key to upgrade to Windows 10 as its asking me to upgrade now.