The UK's armed services will have specialist training at the college
The company in charge of building a £12bn defence academy has received a £29m contract from the Ministry of Defence for early work on the project.
The Defence Technical College at St Athan in the Vale of Glamorgan stands to create more than 2,000 jobs and provide specialist military training.
Last week the UK government announced a final decision on the project would be delayed until the summer.
Local MP John Smith said the government remained committed to the academy.
The Metrix consortium, which will build and run the new academy, said the "early works" contract would ready the site for full-scale construction once the final go-ahead was given.
The first stage will involve moving an RAF training school to a temporary location to allow demolition of existing buildings and preparatory works.
The Vale of Glamorgan council granted planning permission for the project in September, but the final decision rests with the UK government.
Announcing a delay to the academy's approval timescale, armed forces minister Bill Rammell said extra work on the deal meant plans to make a decision in the spring needed to be put back to the summer.
Construction was due to begin late this year, with the college billed to provide specialist engineering, communications and information systems training to all the UK's armed forces, bringing them together in one location on new premises.
Tom Anderson, commercial director of the Metrix team, said: The EW contract provides Metrix with a year's head start on an important body of site preparation activities, meaning that when the overall Defence Training Review (DTR) Package 1 Project contract is signed, work can begin immediately on the full-scale construction of the Defence Technical College."
Vale of Glamorgan MP John Smith called the announcement good news for the Welsh economy.
"I want people here in the Vale of Glamorgan to know that this government has no intention of turning its back on this part of Wales.
"That's why the government has underwritten over £110m of essential works linked with the St Athan project.
"This is a major milestone which takes us closer to the delivery of the project at St Athan."
The planned academy will combine training for all armed forces in the UK