The most useful site to check out is
www.seat61.com - full of lots of useful information.
Amsterdam has very good international rail links so it may be that you don't need to go via London and Eurostar.
There are an increasing number of high-speed services with some kind of bike-carrying facilities, but you'll probably find you need to put your bike in a bag. I'd recommend the Ground Effect Tardis which is a good size for train luggage racks, and when you get to your destination you can fold it up and put it in the post.
One thing to bear in mind is that officially, non-folding bikes aren't allowed on the sleeper services between France and Italy - although you might be able to carry one that had been dismantled.
The German railways timetable site is very useful in that it has an option that allows you to search for trains on which you can take bikes.
PS (for Arch) you can take unbagged bikes on Eurostar (but it's something like £20 each way).