The deal will see the winning bidder commit to building an extra 800 extra care facilities and operating them for 25 years, with the option to extend by the same period.
Its partner will design, build, operate and maintain accommodation that will include mixed tenure extra care units.
The successful consortium will be required to sell, let and manage the extra care schemes.
The council will supply the land and will let sites to one bidder or split the contract into two lots worth £42m each.
PQQs need to be returned by the end of May and can be obtained from firstname.lastname@example.org