I've  not been able to find any info on how to best upgrade from 4.8 to 4.9. Can anyone advise? Also - can anyone make any recommendations on an image gallery module to run it 4.8 (or 4.9 if I upgrade)?  I've noticed a lot of other open source projects have these modules, but I've not found one for DNN yet.

All that you have to do to upgrade your 4.8.x site to 4.9.x is:

• Download the 4.9.x UPGRADE package from DotNetNuke.com
• Uzip that file into your web directory (on top of your existing site)
• Browse to your site and watch the upgrade proceed

And a few disclaimers and sensible things to do first.

• make copies of your existing database and web directory in the event that something doesn't go well
• do the upgrade first on a developmental site away from your live site.  Then give it a good test to make sure that the upgrade succeeded.
  

And a couple of other things

• If the live site has user contributed content, you might want to take the site down while you are upgrading.  You can do this by placing a file named app_offline.htm in your web directory.  It can be simple or elaborate, but just use some html to let people know that the site is down for maintenance and roughly when it will return to service.
• Set autoupgrade=false in web.config.  This should prevent a casual user from triggering the upgrade.

NOTE that there is no longer a requirement to manually edit the old web.config into a new one.  In fact, this process will work if your site is 4.6.2 or newer.

I am a little confused about upgrading. I have my DNN space hosted with the server and got it directly through their own services. Do they automatically give me the upgrade do you think? Otherwise how would I upgrade when the only way I can get into my DNN space is via my login and user interface? I have no access to any database files, but only to the module content files.
If I can also reiterate the question posted by rdo2006 regarding an image gallery module.
Mozzie

You could contact your hosting provider and ask if they can upgrade the website for you, however make sure that they create a backup of your website first.

Personally, I would contact your hosting provider and ask them for a backup of all of your files (including database). I would ask for this even if your hosting provider is going to do the backup for you because one day your server may break and you may lose your website data. This has happened to me in the past and I lost my entire website.

Once you have a backup of your files, you can test doing an upgrade on a localhost installation, and then you can run the upgrade on the live website. To upgrade DotNetNuke you do not need access to the database, all you will need to do is upload the upgrade files via FTP over the top of your current DotNetNuke installation files.

For further information on upgrading, this tutorial may be useful, it is for earlier versions of DotNetNuke but the same principles still apply.

How to Upgrade DotNetNuke v3.x to v4.4.1

How to backup a live hosted DotNetNuke website and restore it to a localhost installation

• How to install DotNetNuke to Vista
• How to install DotNetNuke 4.5 to Windows XP Pro with IIS

Regarding image gallery, you may want to look at www.ventrian.com simple gallery module

One thing I would add to the steps above--when you download the zip files, M$ has managed to make things more difficult for us by adding tags to 'uncertified' files that are downloaded. So before you unzip anything, you need to right click on the zip files, select properties, and then 'unblock' the file. Don't ask me why microsoft is so stupid. You'd be asking the fool who has purchased 3 Vista machines, which make really good doorstops--if not anything else!

Thanks for the tip andy

Are you referring to the UAC "feature" in Vista?