Are you flying into London? (Heathrow or Gatwick?) Or maybe Manchester or Birmingham, and want to get to Bike Tours UK headquarters in Nottingham?
The cheapest way to get across the country is catch a bus. Trains can be unreliable, expensive, and often have complex booking and pricing policies.
A National Express coach can be an economical and direct alternative. Just pick a route with minimal stops. The only downside is, they can be delayed by traffic jams from time to time - just like cars.