I only have about 85 pages on http://www.smstoday.co.uk, but SG is not picking up the description for the home page or pages & sub-folders in http://www.smstoday.co.uk/blog/ folder. (about 30 pages in total).

May be worth noting that I link to the .html pages in the /blog/ and sub-folders, where as link to just the folder path for all of the pages that aren't experiencing the problem.

Downloaded and bought it today so I'm assume 4.1 is the latest version.

Pulling my hair out. any advice is welcome.

**ADDED**

Am I right in thinking that actual sitemap doesn't include the description and that it's just for my own records, as such?

You have me a little confused...I'm not exactly sure what your issue is.

If you're running the spider and the title is not being found in a lot of your pages but you know the title exists, then:
Shortly after v4.1 came out, for one day it didn't find all page titles. It was found and fixed right away.
The v4.1 available on the webpage has that fix. You can also download v4.1.2 Beta at:
http://www.iarchitect.net/Uploads/106/SGv4.1.2.zip

It's not a complete installation package (beta release...it's been thoroughly tested).
Just unzip the files to the software installation directory (and overwrite the existing versions).
Default installation directory: C:\Program Files\iArchitect\iArchitect Sitemap Generator\

The sitemap.xml file will not contain the title. This is gathered for the HTML sitemaps.
So maybe everything is working as expected.
Please let me know so I know if I need to investigate for you.

Thanks,
Brian

Great! I like these easy issues that just need explanation.
Locking topic as issue has been explained.