Yes it does mention chalets in the sleeping acocmmodation guidance, I know there are numerous opinions on this, I have heard Dr Rosemary Everton give her views on this- her view at the time was that they are not domestic premises and therfore are subject to the Order. I dont think the DCLG have given any further guidance on this yet.
Another angle is trading standards. Certainly in terms of furniture, gas installations etc the supply of these goods in rented accommodation in the course of a business is considered to be a hire transaction and is coverd by all the consumer safety legislation and specific safety regulations. This is the concern of the county trading standards department, whilst serious property defects would be dealt with by the environmental health officer if a tenant may be at risk of injury.