How do I get stamps to make an appearance at my son's 5th birthday party in havant. I would do/pay anything to make my son's day

My son watches stampy videos religously and it would make him so happy if joeseph could come and say hello. We live in havant. His birthday is on 11th jan and we will be having a little party on Sunday 10th Jan. Please let me know if this is at all possible xx