Hi Dave,
I guess it comes down to the work you want to be producing in your own time on a freelance basis, what work do you enjoy doing more? is it the illustration work because the day job is very corporate, or has that just happened as a result of the blog?
One suggestion I have for you either way is to get your own domain & hosting, no matter how good the design, a website at name.blogspot.com is always going to come off as less professional than yournamedesign.co.uk in my view, perhaps the same for your clients? It's easy enough to setup a Wordpress theme so you can continue blogging from the domain, that way you could then separate a portfolio and blog posts, or even keep your existing blog and use a new domain for purely commercial portfolio, contact, etc.
I think deciding which work you want to undertake in your own time is key to pushing forward with the new identity, I think the name could easily take you either way so that's not the problem, and of course not to say one way means you can't do both types of work, just that having a style in mind should help get your identity positioning right for the bulk of clients you want to attract, if that makes any sense?
Greg