Page not found – can't log into dashboard

seems weird, I check your site..
all error 404 because your site structure is “https://www.marykingphotography.co.uk/newbornbabyfamilyphotographycambridge/…”
instead of
“https://www.marykingphotography.co.uk/…”

I think something broke your wp setting.
you need to look at wp-config.php and fix the wp directory there.

what plugin you use to add that keywords?
or maybe try to remove that plugin via FTP.

Ididn’t use a plug in , I just typed it in the text. The problem is i cant access the entire thing to change anything, and im a bit clueless of how to do much.

I know probably really stupid, i added that extra bit of text after .co.uk and then deleted it but now it’s still there and I cant get into dashboard to change it.

Don’t give up.

Are you able to access your cpanel?
You can fix wp-config.php via file manager there.

Please check this post: https://asknoypi.com/2015/08/03/wordpress-cannot-login-after-domain-url-change/

This will guide you on where to locate your wp-config.php
Let us know if this helps.