Can I customise comments success and failure page?

Note: new to WordPress this is my first installation and I am not completely familiar with php
When someone posts a comment they either get
1. a white page with text in the top left for example ‘Error: please type a comment.’
or
2.they are redirected back to the page where they have posted the comment

This works OK but I’d like to style the error page (the white page with text in the top left) so it looks like the rest of the site and to point successful comments to a thank you page.

I have tried to style the error page and this works but in doing so it stops the redirection from working. The file I have amended is wp-comments-post.php I did think that perhaps I should have been amending something in my theme but I could not work out which files to amend and how.

Any help appreciated.