Formal letter asking information

I want to know if this letter was written in the correct way.

Dear sir or madan:

I am writing to enquire about the advertisement in our local paper which mentions lots of exciting outdoor activities to choose from. I am very interested, but I need some further information. First of all, could you please let me know if there is any pony trekking?

I would also like to know if the self-catering is included in a large group of seven and how much it would cost?

I am planning to spend four days in your resort with my whole family, that included my children, I would be grateful if you could tell me that you accept children.

I llok forward to hearing from you as soon as possible so that we can arrange the fligth tickets.

Your faithfully

Maria Carew