I have been using Multiplay for more than a year now for my small 8 player server.
They have data centers in a lot of places, i personally have my server in Amsterdam, but they have servers in London too.
There is FTP access, and they provide a config file for filezilla in their control panel (Clanforge), it's very easy to get acces and changes files around (for updating mods/modpacks). They have some of the modpacks buildt into their system so you can just choose the profile and the system makes sure you get the right pack on your server, but i prefer to do it on my own, which is relatively easy.
Here's a link to their shop page:
http://www.multiplaygameservers.com/game-servers/mc-minecraft/
I'll be glad to answer any questions about them. I'll recommend them for sure at least
