I can't see cellular option in settings on my iphone 6 due to this I can't open my wifi hotspot

Since you using U.K english for the language, Cellular is referred to as Mobile Data.

Beyond that, Personal Hotspot is a carrier feature. Make sure your carrier supports it, and is allowed in your Mobile Data plan.

You would need to contact your Mobile Carrier and inquire about the availability of Personal Hotspot with them.

Hello,

For you Cellular is named Mobile Data.

Simply tap on Mobile Data, and you should see the Personal Hotspot.

If Personal Hotspot isn't there, contact your carrier and see if you plan supports it.