You must have installed the wordpress on some folder rather than the root of your website.
So if you want to redirect all the traffic form “sample.co.uk” to “sample.co.uk/wp/” then use the following codes on the .htaccess file on the root (sample.co.uk/)
<ifmodule mod_rewrite.c="">RewriteEngine On
RewriteRule ^$ /wp/ [R=301]</ifmodule>
OR
RewriteEngine on
RewriteRule ^([/]+)$ wp/$1 [L,R=301]
OR
RedirectMatch permanent ^/$ http://sample.co.uk/wp
Although I will recommend to use the 1st one.