Google finds loads of
translation services. Wouldn't think it would be too expensive for one advert.
But, as Paddy says, most Scandinavians have very good English. Also, if the ad is in English, respondents are less likely to expect to have contact with someone who speaks Danish! I can picture you picking up the phone and having someone speaking very fast Danish on the other end
Depending on the tone of your ad, you could add a line on the bottom - something like "Apologies for using English, but my school in Britain did not teach Danish..."
Or, if you have other languages, mention them since even if they don't have good English you might have another language in common they feel more confident using. On a school exchange trip to Holland back in the 50s I stayed with a family where the son (the swop) was learning 7 languages - his sister was learning 9, the extras being Latin and ancient Greek. As they said, who outside Holland learns Dutch?
