Wish to purchase property. Commercial tenant has no formal contract.

We have found a Commercial property for sale which we would like to convert to Residential. The issue we have is that there is a Company in the building who have been there for over 4 years without any formal contract from the owner who has now gone into liquidation. The tenant has rights and I am aware we will have to employ a solicitor to see if it is possible to gain vacant possession. Has anyone had any experiences with solicitors costs, compensation payments and time frame, indeed if it is possible at all.

Thank you