have you try to make a backup of the old website and upload the backup in the new website, in this case in the main domain.
Normally I use the plugin “wordpress all in one” to do this. I do not know if this is a possibility for you, but should work just fine.
once your website url is mydomain.co.uk/Blog/ the new url will be mydomain.co.uk, and the pages will be in your url/page1
