This is good news and from my vague understanding it won't require huge investment in tracks since HS1 is already built to the superior European Loading Gauge; the biggest changes will be building facilities at the German stations and the legalese. But, if anyone involved is reading, please, please, please: sleeper trains from London. I want to fall asleep in Kent and wake up in Berlin, Warsaw, Vienna, Rome, etc. Ideally I'd also like to know which city I'll be waking up in but really I'm not picky.

Please no, we're already spending 60 billion on like 30 miles of 'high' speed rail, a direct rail link to germany would suck in so much cash it would probably implode the entire world economy somehow.
(Not a dig against rail just the UKs incredible ability to spend gargantuan amounts of money for almost nothing)