Don't know why I didn't realize you said gb not mb for your photos lol. Not sure how much space Piwigo allows, but that could be a good option for storage of the photos.
I would definitely try some google searches. S-Drive doesn't have a plan that large either, but they may be willing to alter a plan for you too, I'd ask them also.
The photo gallery will work with images stored on another server. You would need to alter the .xml file to point to the location of the images, but that's pretty easy to do since you would need to put the full URL into the path for each image.
Having said that, it would be an extreme job to do that for 30gb of images. I can't imagine the number of hours it would take to do this. On the other hand if you have good skills for Find/Replace setups, then you could theoretically use the HTML Editor to find and replace all the paths to include the correct ones. There are lots of ways around it I guess is what I'm saying so yes it will read images stored on other servers.
So many options lol, but I'd definitely search around before settling with any host to make sure you'll be getting what you need for the best price.