I'm confused.. It's asking me to change my name servers to the 123.reg default but do I want to do that if they're currently pointing to ns1.wordpress.com? My website is a wordpress website...
You can’t manage your DNS via 123-reg if you use 3rd party nameservers. You will need to manage it via Wordpress or ask them to do it on your behalf.
If you change your nameservers to 123-reg your site will stop working, so don’t do that.