I let a 1 bedroom, single storey cottage all on one floor with a front and back door. The bedroom has no external door and windows that are not big enough to get out of in the case of a fire. Does this room have to have a fire escape directly to the outside. (i.e do I need to fit bigger windows) Thanks

It all depends on the layout of your cottage whether your premises could be considered to have a satisfactory mean of escape. You do not need an external door from the room you intend to let and only if you replace your window does it need to have an escape window fitted. Without a physical survey (Fire Risk Assessment) it is impossible to give you a definitive answer.

However you you should have a domestic fire alarm fitted in accordance with BS 5839-6:2013 for your own safety and anybody else in the cottage also check out https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/11085/payingguests.pdf for more information