Hi Linjeakel,
They pushed back the release of The Tsunami Countdown to get one more Tyler Locke book under our belts in the UK before it comes out. It's set for publication on December 6 of this year, and I'm sure there will be a Kindle version as well, even if it's not up for pre-order yet (they may be waiting until we have a cover design). I doubt you could publish a book these days without a Kindle version.
There will definitely be a Kindle version of The Roswell Conspiracy as well. It comes out May 31 in Australia and July 19 in the UK. No word yet on a title or release date in the US.
The Catalyst isn't actually supposed to be on sale in the UK. That's a gray-market listing for the US version (probably used or unauthorized import), which is why there isn't a Kindle edition. I don't have a title or release date yet for the UK version, but I'd guess sometime next year.
Hope that clears it up. The confusion comes because I have different publishers in the US and UK, and they each have exclusive rights to their own markets.