You just donate what ever you like as it is classed as a charity. They have all sorts of buns, some are just handed in to them if the owners dont want them any more, they aren't all stock buns that have got to old as sometimes suggested on here.
Both my buns where from there. Buster was an unwanted christmas present so was tanken back to them, he was 17weeks when i got him and Lola was really over weight and just a chore to her owners so they signed her over to p@h, she is 4yrs old.