The redevelopment of the former Park High School will involve a three-story block being demolished and replaced by a new building and a large open space for its 1,100 pupils to use.
The new central building will link to two existing buildings that are to be extensively refurbished.
Project manager Brian Siller said the academy would be building on the recent improvements made before the Government spending review.
Siller, who works for academy partner Morston Assets, said there should be minimal disruption during the three phases of construction, and students were not expected to be relocated to portable buildings.
A detailed planning application is likely to be submitted in the next few weeks and, if approved, work is penciled to start in March.