For the Germans it was easier, though Guderian's persistence did matter, because they were limited in army size (in theory) it gave them better firepower. Also unlike the British they had no vested interest to protect.
For the British there would be problems - where would armoured formations be used? After WW1 its main areas of combat would more likely be the Empire in minor 'brush-fire' conflicts. Yet, it had the experience, the technical no-how, and officers who could see the potential. I think I am right in saying that none of the 'commanders' of the tank formations that fought successfully in the Salisbury Plain manoeuvres of 1935 (?) saw WW2 active service with tanks - e.g. Broadhurst, Pile & Martel.
Yet it doesn't seem implausible to think that Fuller's & Hobart's ideas could have been acted upon - if the Treasury would allow the funding!! Maybe then the BEF would have been wholly armoured - and with decent tanks!!