Sorry for the misunderstanding, I thought multisite admin area was still needed even though they were separate databases. Obviously got confused there.
I’ve installed 2 different WordPress’ and put the new website installation in a folder called ‘mainsite’ within the default directory. Created a wp-config file successfully, can log into the backend no problems, set my URL to mysite.com/mainsite and presented with a 404 error when visiting the site?!
Do you have any ideas as to why that would be. Admittedly, this is in the incorrect forum now sorry.