There's lots of great cycling in Europe. Have a look at this site http://www.ecf.com/
for information. The Eurovelo link will give you lots of information about the longer routes. One of my favorites is the Loire. It's great cycling, lovely scenery, plenty of campsites and lots of interesting towns.
I'd also suggest you join the Youth Hostel Association, good for inexpensive accommodation. For the UK, check out http://www.sustrans.org.uk/
They can provide maps of a number of really good cycling routes. I particularly recommend the Rievers Route and the C to C.
In Germany, as mentioned above, there are some excellent routes. I haven't tried them (yet) but the Rhine and Danube routes are supposed to be excellent.
You will find drivers in Europe are generally considerate to cyclists and in many cases, downright friendly. The only exceptions seems to be Spanish truckers!
You'll have a great time.