I've been a t.A.T.u. fan for 6 years. I totally prefer Lena Katina's solo work over Yulia/Julia Volkova's. Katina's only released a debut single with two songs on it, and recorded with Belanova, The Rasmus, and Abandon All Ships so far, but she has a few singles that are up on youtube that aren't on iTunes yet. They are "Lost in This Dance" and "Waiting." Except for "Keep On Breathing," but that's on a site called kroogi, where you can buy it, and it goes to Japanese charity. Katina also has some upcoming songs, like "So Not Cool" (aka "The Beast), "IRS," "Just a Day," and "World." I have NO idea when she is going to release all of these songs; whether they will be singles or on an entire album. But I think she said she's been throwing a lot of ideas for now. Hopefully, her debut album will have more than the songs I mentioned. I'm excited!
As for Volkova...Her debut Russian single, "Sdvinu Mir," is on her youtube. The English version, "All Because of You," is also on youtube. She also has three unreleased youtube singles called "Rage," "Woman All the Way Down," and a snippet of "Stand Up." I don't know whether "Stand Up" will have a full version or not. She said "Woman All the Way Down" will NOT be on her debut album. She has not released anything on iTunes.
I'm not exactly all that excited for Volkova's work. I like it, but I'm not that big on it.