House purchase budget

Hello, we are in renegotiations with a house purchase. Asbestos found as expected but more throughout the house than we expected.

It is easier to budget for places I know I can remove it. Or leave it undisturbed. But as we will be doing extensive modernization, including re-wire and re-plumbing I worry about unknown costs to existing budget lines for places that need avoided but may be exposed.

Especially as there are Packers below Floor Joists - In the small ceiling void above the Pantry, there are small offcuts of boards used as packers where the timber floor joists extend over the supporting blockwork walls. These packer boards have been confirmed as being AIB and I strongly suspect that similar packer boards are present elsewhere within the property within the suspended timber floor construction. Which is ground floor and first floor.

I got this feedback from surveyor as well

The AIB packers are under the floor joists and so shouldn’t be disturbed provided the contractor takes care and isn’t too heavy-handed.

Wondering if I am right to pad out budget to compensate that contractors are going to find that hard to work with and increase their quote due to timelines and PPE etc?

Any advice helps, although it is a bit of a “how long is a piece of string?” Question.