The British Isles are far from Japan, even if an agreement were immediately reached and shipping were arranged from London, the goods would not arrive until two months later.
Moreover, armored troops are a technical branch. Familiarization with the equipment and basic training also require time. It would be considered highly efficient if they could be deployed in the battlefield within six months.
As for the current Russo-Japanese War, it could only be considered a distant solution. To quench the immediate thirst, the Japanese Army must exert its own efforts.
In this matter, no one could offer assistance. When it came to the specific tactical command capabilities, the frontline officers were obviously more capable than the government officials.
If the professionals couldn't handle it, amateurs were even more out of the question. Japan's resources were thin and could not withstand any squandering; it was not yet time to act recklessly.