With regards to choosing your domain name, It doesn't matter so much these days. It used to be the case that you would get a lot of SEO benefit from having your keywords in the domain, but with recent updates to Googles algorithm this is of less importance.
However there is still some benefit, so we would generally recommend you go for the more generic approach by using [your town / county] plus [type of property] as the domain e.g. "NorthDevonCottage.co.uk". Or combine the name of your accommodation with the location e.g. "SeavViewCottageNorthDevon.co.uk".
However if you want to just use the name of your accommodation on it's own, that's fine too. As long as you optimise your website content for relevant search terms (specifically on the homepage) and get some links pointing to your website from other relevant websites, you will still rank well.
As for the website name (the name that appears at the top of each page of your PromoteMyPlace website), this can be different from the domain name and you can set this to whatever you want, without having a detrimental impact on your search engine rankings.