A) If the birds were intended for consumption by yourself or friends and family, then the carcases are regarded as household waste. You may dispose of them along with other kitchen waste by putting them in black bin bags or dealing with them as advised by your local authority.
If, however, you are operating a food business and the meat was for sale to your customers, then the carcases are trade waste and must be disposed of by a person authorised under Section 34 of the 1990 Environmental Protection Act. In this case, it would be worthwhile contacting either a local wholesale butcher or your nearest hunt kennels to see if they could assist you. You should expect to pay a fee for disposal.