I'd never heard of these plans, so I did some research, don't know if you found this out already.
The 10th Anniversary Edition soundtrack was indeed released in the UK. Unfortunately it doesn't include any new material - it's just the regular Titanic soundtrack and the "Back to Titanic" CD packaged together.
We could really use some more Titanic music, especially for the 10th Anniversary!
>>Unfortunately it doesn't include any new material <<
It' very rare that anniversey editions of anything ever do, soundtracks or films. For the most part, it's the same old thing in new packaging aimed at a new market. If there ever is anything new, you'll see it offered as bonus material, director's cut, or something along those lines.