Would Drupal be a good CMS to use for...
 

A basic social network type site? (Members can upload images, comment on other images, message other members, write short blog posts)

Or would I be better coding a complete CMS from scratch in PHP / MySql?

I"ve never used Drupal but consider myself quite well versed with Wordpress if that helps.

Any advice would be great.

Thanks in advance

Drupal is a very good and capable CMS and is more than capable of doing what you want.

THat being said, it has a steep learning code and is nothing like working with WP

If you plan to code a cms from scratch, you're completely nuts or a fucking genius, or both ;-) I would never reinvent the wheel, unless I have a completely new idea of wheel.

Drupal is good and has a great supporting community, but If I were to build a "social network type site", i would look for something more specific. there's stuff around that can get you started with almost no customization.. take a look:

http://www.google.de/search?q=social+network+scripts

yes, drupal will be great.

But like someone already said, there is A LOT to learn, this is one massive CMS

I use Drupal, and think it's great. However if you're a "code my own CMS" type of person, you'll likely be frustrated with how much you have to learn in order to get X done, when you could do X manually much faster.

In my case, it's the opposite. I'm able to get things done in a day by myself that I would have had to pay thousands of dollars to some coder to do for me, and then pay him to fix and upgrade, etc etc.

Drupal isn't anything like Wordpress though. Certain things Drupal lags behind in (themes, wysiwyg editors, link masking, time to launch) while others it excels in. I use both for different purposes.

I've looked into using a social network script, but there are just SO MANY I wouldn't know which to use.

Any suggestions?

You could use Joomla and JomSocial. Seen a few sites go this way. If you go with Joomla make sure you have a dedicated server, it is slow on a virtual set up.

http://www.jomsocial.com/

go for custom made., drupal is vast and needs lot to learn and customisation, instead u could build custom one, in that time/efforts.