For a first tour, especially when you've not done much cycling before, I can highly recommend Holland.
Getting there is easy via an overnight ferry from Harwich to the Hook of Holland.
When you're there campsites are plentiful, the people are really friendly, and it's flat! As well as the big factor, Holland's cycle network is second to none, you'll barely be cycling on a road, you'll be on beautiful, smooth tarmac cycle paths the whole time.
Plus you can get a bit spliffed up if you go to the right places too
