Content Delivery Networks
Most good content delivery networks will have a vast network of servers in various locations in US, EUROPE and ASIA. While you care little about US and ASIA its not relevant that your files will be cloned on these networks as most CDN's the price includes all these networks within the set profit margins and therefor will not cost you any extra.
Nowadays most servers use fail proof raid setups and the only risk they face is freak fires that could damage all of the disks on the array at once, but with content delivery networks because they are mirroring your files all over the global it essential means data is never at risk on any of these problems.
Europe users will get served from files within Europe's data centers
So, hosting images on any good content delivery network will mirror your files in various locations across the globe, now the important bit about this is that files are downloaded from the nearest data center, so if you have 90% of your users accessing your images in Europe then your files will transferred from a server in Europe, meaning that your users will get great speeds and well if you have a few users occasionally in the US then they too will get great speeds.
Answering your question
Since content delivery networks do not process PHP and SQL Databases and only static files you will need a
web server + cdn. You could have a Amazon S3 + Rackspace Cloudfiles, you can use any combination you prefer. CDN's vary in price on storage and transfer, some only charge transfer out, while some charge both in and out, you will have to pick one that you feel comfortable with and what meets your requirements.