It is only unlicensed if the risks of fibre release are low. The asbestos containing materials must be in good condition and are only sporadically disturbed in a manner that emit very low amounts of fibres. Sanding an ACM is not unlicensed and I would suggest it is notifyable licenced work or very high risk. However to decide you have to carry out a risk assessment. You should have an asbestos survey that should give you some guidance. If the works are substantial you will need a refurbishment / demolition survey as opposed to a management survey. In areas where all the asbestos is encapsulated and not being disturbed then asbestos awareness training should be ok. It is a bit of a read but you need to read the ACOP and guides on the HSE site.

I know a lot of contractors that would! They likely would not call it sanding but preparation work?

The question was quite specific and interesting. It was, and I paraphrase, "when does work on or near ACM become "work with asbestos"?" For once I'll resort to quoting the regs . (2) A reference to work with asbestos in these Regulations includes— (a) work which consists of the removal, repair or disturbance of asbestos or materials containing asbestos; (b) work which is ancillary to such work; and (c) supervision of such work and such ancillary work. So if you are not removing repairing or disturbing ACM then its not "work with asbestos". If you are just putting a new coat of paint over the top of existing well maintained asbestos then you aren't working with asbestos - . So the question of licensed or unlicensed doesn't arise. Obviously awareness training is essential because then your workforce will be able to look out for warning signs such as damage that might have resulted in release of fibres. They'll also be aware that if they need to get the putty knife out and do some filling then at that point they might well be undertaking "work with asbestos".