"But we have a modern building..."
Every non-domestic premise built before 1999 is required to manage the risks from asbestos whether there is any present or not. Remember, materials must be strongly presumed to be asbestos until proven otherwise.
"We lease the premises - so who's responsible?"
The person who is responsible for the maintenance and the general up keep of the building is responsible for the asbestos register. Various situations can arise by which either a landlord or a tenant can be held responsible.

"Can we get financial help?"
As part of it's urban regeneration scheme, the govenment has introduced 150% tax relief for companies incurring expenditure on land remediation, including buildings.
The costs of project managing asbestos within existing buildings can be set against company profits as tax relief. For example, if £50,000 is spent on removing asbestos, £75,000 can be deducted from taxable profits. Part of the professional fees, preliminaries, survey fees, and possibly the reinstatement expenditure, may also qualify depending on the nature of the project.