Thanks for your help. Ok, basically I am using Wix HTML5, which doesn't support blogs. So their instructions are to add a CNAME record to create a subdomain "blog.mysite.co.uk" and then point it to the IP of my wordpress blog "consula.wordpress.com" and add this to wordpress as the domain.
So, just to clarify, if I set up a subdomain and follow the Wix instructions, will I need to change the nameservers (which the Wix instructions don't refer to). I don't want to undermine my main website you see.
The wix instructions are: http://www.wix.com/support/main/html5/wix-editor/blogs/using-wordpress
And for CNAME: http://www.wix.com/support/main/html5/domains-email/managing-your-domain-records#weight-5
If you could please just clarify the position before I do anything as I am not a techie, so apologies for my ignorance, I just don't want to do anything that would affect my main website.
Assuming that this can be acheived and that I can have my subdomain pointing to the blog and the nameserver thing will only relate to the subdomain, then I can pay for the wordpress upgrade with confidence.