It often a good idea for leaseholders to first informally approach the freeholder to try and acquire the freehold reversion of their building. This is an issue of informal negotiation. No legal right to purchase the freehold exists and consequently you cannot apply to the Leasehold Valuation Tribunal to determine any terms.
However, depending on the nature of any agreement it may be enforceable through a County Court. Fridaysmove leasehold extension team would be happy to talk to you prior to any informal negotiations.