After serious thinking Andy wrote :
No, not at the moment. The facias are ok - and all upvc. The soffit boards
are well underneath, and are not.

The usual soffit panels hook onto a ledge in the L shaped facia at one
side, then into a U shaped plastic channel fixed at the wall end. So
not normally any need for fixings apart from for the U along the wall.

I wouldn't really expect nails to work very well into asbestos - you
would need to drill a pilot hole through to the underlying wood. Screws
would be better and much more secure, but what ever you use needs to be
stainless or solid brass rather than brass plated.

I nailed my facias up, then screwed through gutter and fascia with 2"
solid brass screws.