How and What to change to move WP site within my hosting.

Happy Friday Awesome WordPressers!

Thanks to your help I have now finished modifying a WP site for a client. I’ve succesfuly migrated it onto his hosting service. However, the site was installed as http://theroofingcrew.co.uk/blog and I need to change it just to http://theroofingcrew.co.uk

I’ve tried just changing it in the database wp-options but that just breaks the site. I’m thinking this should be an easy one but yet don’t want to venture any further and risk screwing up the migration which was a bit tricky to begin with.

As always any help will be much appreciated! Oh, his hosting service is at 123-reg.co.uk.

Thanks!