HMO ATTIC ROOM REGS

I have an attic room on the third floor which i want to rent. It is large and there is a large window open which can be reached if you stand on a chair to get you on the roof . I do not know what the minimum standard is and concerned that this may not pass the HMO regulations for fire escape as there is no other way out if there was a fire on the second floor.

Can someone please point me in the right direction before I start to fill in all the paper etc

Regards