The formalisation of a deal that was announced in July eases uncertainty for Japan's motor industry giants.
Developer Panatonni says no contracts have been signed, but it is having "exciting" discussions.
The Japanese car making giants aimed to combine their businesses to compete against Chinese rivals.
The firms want to strengthen their offerings in the face of Chinese competition in the electric vehicle sector.
In March, the two Japanese car makers agreed to explore a strategic partnership for electric vehicles.
Organisers say motorcycle riders will be parading their bikes decked out in neon lights.
Toyota has apologised for providing incorrect or manipulated data for safety certification tests.
Panattoni Park will create "thousands and thousands" of jobs, Rishi Sunak says.
A developer has permission to knock down the factory and instead put up 11 new buildings.
