You are very likely to hear back from Jimmy Carr. He is great to his fans .

Stephen Fry replied to the letter I sent quite quickly and signed the photo I sent, I believe that if you send just a letter and SAE he'll send his own.

It won't take very long to look through the feedback on this site to answer your own question, look at several for each. It's what it's there for, and is a really interesting way to get a hold of signing habits.

There is a thread here somewhere (not sure exactly where, but have a look for it) on "who is sec/autopen" which is a bit shambolic but is useful.

With a few notable exceptions (none of whom are on your list), if someone is hugely extremely famous and people are reporting getting sigs back in about a week or two, then they are very unlikely to be genuinely signed by the celebrity in question.

Most of those people you will not hear back from

Stephen Fry's a good TTM signer-You'll get an authentic from him

Morgan Freeman sends PPs.

Your Orlando Bloom autograph will come back as an autopen.
Paul McCartney is VERY rare and hard to get through the mail.
Cameron Diaz's has some controversy-some say hers are secretarial.
Emma Watson sends out preprints.
There's some speculation going on about Leonardo DiCaprio's through the mail autographs too.

Over the past week I have sent SASE to all of the below,

Tom Hanks, Paolo Nutini, Kevin Spacey, Cameron Diaz, Orlando Bloom, Sir Alex Ferguson, Craig Ferguson, Tom Cruise, Amy Macdonald, Charley Boorman, Lewis Hamilton, jenson Button, Leonardo Dicaprio, Paul Weller, Paul McCartney, Robbie Williams, Robbie Coltrane, Jimmy Carr, Ricky Gervais, Richard Attenborough, Stephen Fry, Sean Connery, Nicolas Cage, Steve Carell, Roger Federer, Robert pattinson, Bill Clinton, Kate Winslet, Danny Boyle, Emma Watson, Piers Morgan, Dannii Minogue, Russell Brand, Amanda Holden, Ian Brown, Matt Damon, Morgan Freeman, Robin Williams, Steve Martin, Clint Eastwood, Kevin Costner, Katy Perry.

What are my chances of getting replies? Who can I hope to get a reply from and who will be difficult to get? Thanks.