Multisite URL redirect problem

I have been over no end of tutorials and had contact with ISP support but cannot get this sorted. They told me to go down this route, which I am happy to do.

Our main site is https://www.contemporaryenergy.co.uk

I have developed a WP site in https://contemporaryenergy.co.uk/wordpress/OnlineShop/ and it is part of a multisite network.

I currently have a .htaccess redirect which sends users who type contemporaryenergy.co.uk across to https://contemporaryenergy.co.uk/wordpress/OnlineShop/

So far so good. That is working as it should.

What I cannot get my head around is how to rename https://contemporaryenergy.co.uk/wordpress/OnlineShop/ to be just https://contemporaryenergy.co.uk/.

To put simply, I want to make the WP site https://contemporaryenergy.co.uk/, or at least make it APPEAR to users as .co.uk only.

Patrick