Overnight expenses when working away from home?

Our company may soon be undertaking a contract around 2 and a half hours travel from where we are based so we are most likely going to need some employees to stay in accommodationn nearby. We will obviously need to pay for the accomodation and pay them for the inconvenience. The contract is for around 3 years and while some staff may be there full time 5 days a week most will be there as and when they are required. Just unsure as to how any payments are treated with regards to tax. I ume that the cost of accommodation is treated as an expense in the same way as our fuel costs are and is not seen as a taxable benefit to the employee in the same way as a company car is. And is the extra pay they recieve taxable in the same way as overtime would be. any advice would be great as a friend of mine thought there is some kind of tax relief on staying away but i cant find any info on it.