Prince Harry has penned a heartwarming tribute to his children as he approaches his 40th Birthday. The Duke of Sussex will be celebrating the milestone on Sunday, September 15. Prince Harry is continuing his work with the Archewell Foundation, the non-profit organisation he co-founded with wife, Meghan Markle. But above all, his priority remains fatherhood, as he wrote an emotional tribute to Archie, aged five, and Lilibet, aged three. Speaking to People magazine, Prince Harry said: “The best gift I’ve ever been given is, without a doubt, my kids. I enjoy watching them grow every single day, a…