Germany (or Austria).
Massive cycle path network
Even more bike friendly than Holland
'Bett und Bike' (Cycle friendly B&B network, with optional luggage transfer)
Many companies that will organise bike tours for you, including bike rental and luggage transfer and return to start
For maps look at the Estebauer 'bike line' series, some are in English (not that it matters, as it the maps you want)
Easy to get to, Ferry to Hook of Holland and either car or train
Most of the long distance paths, like Holland, follow rivers and canals, so no hills
Sign posed all the way
English widely spoken, to a degree
Proper food, proper beer, better weather than the UK or Holland
Trains actually designed to take Bikes ! that run on time !!!! and are cheap !!!!
My recommendations would be
The Danube cycle path, the classic bit is Passau to Vienna, but the source to Bratislava is all good
The Elbe cycle path, the classic bit is Wittenberg to Decin, but Hamburg to Decin is all good
The Mosel (classic all the way, but far too much wine that just has to be tried)
The Rhine, Bingen to Bonn is the classic bit
The Spey - runs into Berlin, a great city to cycle into
(PS: I've cycle toured in UK, Ireland, Denmark, Belgium, France, Holland, Germany, Austria & Czech Rep)