It’s not easy as I thought. google play store selling that cable for £25 so I looked in to other places. You can get them cheap but apparently they don’t meet to USB-C spec and might damage the device or charger. google engineer call Benson Leung done lots of research on this.
going by what he was saying it’s safe to buy a USB-C charger with USB-C cable with known brands. even to buy USB-C chargers from other phones like Microsoft Lumia 950 XL chargers, you can pick them up cheap.
Moral of the story is don’t buy the cheap cables. It wont save you money.