create a letter layout to multiple persons

[KirstyB]

I have a db woth two tables one is a list of GPs and the other a list of surgeries these are linked by a one-many relationship useing GP practice (ie each surgery can have more than one GP) I wish to do a find based on area and send a standard letter to each GP in the surgeries returned. I have a layout created for the letter but cannot work out how to generate a letter for eacg GP I can do it for each surgery but not for every Gp at the surgery.