The council expects to invite tenders at the end of September after it secures cash from the Regional Growth Fund.
The winning bidder will remove the existing roundabout and widen the M1 spur road to three lanes. This will provide a continuous east-west carriageway with a speed limit of 50mph and eliminate long bottlenecks.
Two new roundabouts will also be built to allow road users to join and leave London Road and the M1 spur.
Information about prequalification can be obtained from Antony Aldridge (tel: 1582546652, email: m1j10a@luton.gov.uk)