It should be safe, Windows 10 is light on most computers out there. It has more features like Cortana and the ability to stream Xbox games with the Xbox app. It also would have support longer than Windows 7 (Even longer if your computer's CPU is a Skylake because Microsoft). I think you should upgrade to it, but, you might want to change or disable some settings that would interfere with privacy.
Is it safe? Yes. Is it worth it? IMHO not really. Window 10 is basically Windows 7 with a reskinned GUI and a bunch of features like OneDrive and Cortana that I personally would never use, though you may be different. You also get DX12, but nothing uses DX12 except that forza demo. However, you will get a telemetry system to track you. Pros, cons, they basically even out. If Windows 7 works for you, then the worthwhileness is debatable.
thanks guys for your feed back , but i dont think i am going to upgrade until windows 7 is no longer suported, but as i said thanks for giving suggestions and noticing
Yeah basically if you want some feature (CPU or DX12 support) then yes, otherwise there is no point whatsoever to upgrade from 7.
Free upgrade to Windows 10, sign into/up to a Microsoft Account, then clean install Win 10 or go back to Win 7
This would massively depend on your specs, what you use your PC for and what you'd prefer. If you do quite a bit in Windows File Explorer, I would recommend you to stick with Windows 7, as with my (and my friends) experience(s), Windows File Explorer crashes a lot in Windows 10. Other than that, and 'Cortana' being incredibly difficult to set up in the U.K, windows 10 should be okay on any nearer to the top of the group low-spec PC's and up. Generally, if your PC can run BeamNG at ~40fps with collisions disabled, you will be fine. It's also worth mentioning some software (very little now) do not run properly, and if this is a problem, you can revert back to Windows 7 very easily. Basically, try it. If you don't like it, revert.