Any answer very much depends on how long you are planning to stay and when. If for only a holiday then there are a number of agents, companies and sites that offer accommodation. You could google under 'cottage Scotland', go to Visit Scotland online, etc. You could also check out such as Aberfoyle Holidays, including phoning them for advice. If for the longer term then the question is whether you want to buy or rent. You should check property agents and solicitors, One way of doing that is to look up the Tayside Solicitors' Property Centre (TSPC).