The country does need a production line of building. Have to hope that they start with one or two locations and move development and work skills around to keep momentum going. Has to be easy to reach work and leisure locations for all the new inhabitants. Agree that flood plains need to be avoided, to prevent the new towns absorbing skilled labour that is needed elsewhere. At one time a street would include a pub, with other things that might be needed not too far away.
Note only one location south of the Thames. Hard to get right. Should it be built first; built as skills can be spared; or built last with the skilled people (who are required to live in the homes they have built - a form of guarantee of quality) commuting from their new homes.