Selling freehold of small block of flats?

I own the freehold of a small block of flats. I also owned all of the leasehold flats (jointly with another), which we sold in the last couple of years.

I now intend to dispose of the freehold and will, of course, offer it to the leaseholders as required. If the leaseholders do not wish to purchase the freehold, however, I understand it cannot subsequently be sold for less than it was offered to them.

So naturally, I’d like to have a formal offer from a willing buyer that I can use for the statutory first-refusal procedure as a reference. I’m aware I can get a surveyor to provide a freehold valuation, but that seems a less good option, given it’s not backed by actual intent to purchase at that value, which could trip me up down the road selling on the open market if the price is set too high.

I am not looking to maximise profit, I’m happy to pass the freehold onto the leaseholders for a lower end of fair market value, but I want to make sure I have viable options should they simply not wish, or agree to, purchase. I’d much value recommendations as to how to proceed and what institutional buyers I can approach that may be a good fit and are likely to engage?

Thank you in advance,

Gabriela