I bought Lenovo Z50-70 but no OS disks. How to install windows if HDD crashes?

I bought a lenovo z50-70 with windows 8.1 installed on it but their is no disks with it. I can create a recovery drive but will it also be useful if my HDD crashes someday. Is their any way to make an OS disk so that I can make it work on this laptop in case HDD crashes someday.
Also, can I repartition my HDD without the need of OS disk and just the recovery drive?
I only have C: drive(890GB) and D: Drive(25 GB) but I wanted atleast 3 drives so that C: contained only installations E:/F: contained setups and D: is for recovery.
So will I be able to do repartitioning without the need of Windows 8.1 disk?

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