What is the procedure of letting properties to the companies?

Answer 1

Most Companies who need rental property (eg for workers seconded from overseas) only deal with Agencies .. locate Agency that deals with Company rentals

Think about it -
1) you are a Company with 30 Engineers coming in next week to rebuild your IT Systems ... which Private Landlord(s) are you going to ring ?
2) You have 30 Engineers in UK for the next 3 months - do you REALLY want to deal with up to a dozen different Landlords / different rates / different Contracts ??