http://www.lynda.com/Dreamweaver-training-tutorials/185-0.html?category=beginner_337 -- not free, but excellent. There is a free trial period that might be helpful to you.
Forget learning Dreamweaver specifically - learn HTML and CSS. Dreamweaver is just a tool which makes the coding of HTML and CSS easier (and its a pretty awesome tool for that).
And then hang out in here in the forums and read up on everything.
http://css-tricks.com/ (the forums, the snippets, Chris' blog posts - all are excellent resources)
Finally for bonus points - read up on Content Managements systems (because if this business is serious about content updates, a CMS is the way to go) and maybe create a free blog at WordPress.com so you can see how they work. Also it may be useful to readup on version control systems (subversion, git or mecurial).
I have to agree with Bemdesign. HTML & CSS code are the 2 essential building blocks to web design. Without these requisite skills, you'll be lost in Dreamweaver.
HTML & CSS Tutorials - http://w3schools.com/
Creating your first web site in DW
Best of luck!
I personally have completed a course at Lynda.com that should give you exactly what you need.
From your description, it doesn't appear you need to be a webmaster:)
This is an excellent beginner course for what I believe you are aiming for. They have the 30 day free trial going on right now. Its a 2h 48m video course. You can pretty much double that time if you do each of the lessons. I recommend getting the asset files if possible. I think there is an extra charge for them though. Plan a day to to do the course and you should be profecient enough to get through the interview:)
Creating a First Web Site with Dreamweaver CS6
Thanks for your help. You are correct the job is not design orientated nor
webmaster. It is a small component of the job that asks you to maintain a
simple website, send out monthly bulletins, design invitations and possible
catalogues, but this is only a small percentage of the job. The main part
is organising and installing exhibitions, projects and public forums.
Thanks again, I'll give Lynda a go, once I can get through the interview I
can continue further tutorials or study at slater date.