The cash will be mainly spent on production facilities at BAE Systems' Barrow-in-Furness, England, nuclear submarine yard; essential long lead items for the submarines; and the nuclear propulsion program being led by Rolls-Royce.
The Conservative government has committed to building four nuclear missile submarines with the first boat entering service in the early 2030s, several years later than originally planned.
The submarines will replace four Vanguard-class boats that first entered service in 1993.
In the latest announcement, BAE gets £225 million for investment in new facilities at Barrow and around £200 million goes for long-lead items.
BAE is midway through a program to build seven Astute-class hunter killer nuclear submarines at the Barrow site.
Included in the funding is a further £136 million investment in the common missile compartment being designed and built in a UK-US collaboration effort.
The compartment is planned to be fitted to the Successor submarines and the US Navy's Ohio-class replacement.
A decision on a manufacturing contract was planned for this year but that approach has been dropped with the government announcing in the SDSR that due to the complexity and scale of the program it will instead adopt a staged approach rather than a single procurement decision.
The next phase of the program will focus on risk reduction and demonstration, the government said in the SDSR
Andrew Chuter is the United Kingdom correspondent for Defense News.