I've recently got back into playing guitar and Rocksmith, but my old cable that came with the game is getting a little unreliable and I have to be quite careful with it else it keeps cutting out.  Are there any replacements you would recommend?  I see quite a few different ones available on Amazon, but some have comments about noticable delays and poor sound (I might well use this for recording in the future too).  I'm in the UK, so would obviously need to be available over here too.

Realtone cables work best in my experience. Aftermarket cables require a patch and don't allow the game to switch voices so you would play with basically a clean sound. 

Again, this is only my experience as I've tried a few different amazon cables, but the gameplay is not the same IMO.

Use a Audio Interface with the RS Asio Driver, a audio interface has minimal latency and is a awesome base to play on your PC in general. I never had a realtone cable.