frankC'est la vie (or as the French

say "that's life"!) Frank...
Assuming Contract Hire, the important thing is that the vehicle is returned to the leasing company at the end of the contract in an appropriate condition for age and mileage (ie not showroom condition, minor stone chips etc OK but not broken glass, stoved-in panels, split rear wings

etc). Otherwise they will levy dehire damage charges. What happens before then is of no concern to them. So get it fixed properly but cheaply! No need to involve the leasing company.
If it's on Finance Lease (usually vans, rarely cars), you will have to dispose of the vehicle and settle the final payment (aka 'balloon"). The condition of the vehicle will affect its value, so if damaged you'll get less and so possibly have to find more to settle the balloon. Whether that's better than paying for the repair and then getting more at disposal is your shout.
