Agree with Carmad, keep your own insurance running on your own car; this is unrelated to your being a named driver on the Motability policy.
For information I am insured on my wife’s Motability car for business use too (I own and run a cat care and sitting business). As Carmad said, this is regarded as beneficial to the Motability customer as I’m bringing income into the household.
2024 - BMW i4 Grand Coupe eDrive 35 Sport
2020 - Volvo XC40 T4 Inscription
2017 - Audi Q3 TFSi Sport S-Tronic