It does, however, have its own exit, numbered 2A to fit in with the M20's junction numbering. The junction is at the far eastern end of the motorway, meaning it passes by Sevenoaks with no access to the town.
The longest distance between motorway exit points in Britain is found - partly - on the M26. Travelling west, after junction 2A, there are signs warning traffic that there is no exit for 18 miles. There is a junction and a service area in this distance, but at neither have you any option but to continue forwards onto the M25. The next exit is M25 J6.
Kent County Council continues to lobby for the installation of a new junction between the M26 and the A225 to improve access to Sevenoaks, which presently has astoundingly bad access to the motorway network despite being pushed up against the M25 and M26. The alternative option is a set of new sliproads at M25 J5 to allow traffic to travel between the M26 and A21, but neither option is being pursued with much enthusiasm by Highways England.