I guess portability is not all that important to me. While I would like to be able to listen to anything I want, say, while I drive, I'm usually content with the radio … and it's not as if I'm going to be driving in England anyway. And while I would like to listen to my music at work, I may not find a job that allows me that luxury.
So, now I'm thinking that, instead of an iPod or any of the other digital music players out there, I might be better off purchasing an external hard drive for my laptop (something I would bring with me to London) or for my server (which would remain here and I would connect to over the internet). This would allow me to record my music in a higher quality format than mp3 and still get everything stored. And there is plenty of software out there that would help me manage my music, if I decide to do such a thing.