The News section at PJSM Prints
is often a good place to check.
I understand that Terry is going to be launching Dodger in September at Ely Cathedral in Cambridgeshire. It's a ticketed event and you can purchase tickets HERE.
As to signings - these are getting a lot rarer these days. Even before the alzheimer's, Terry suffered from Repetitive Strain Injury and signings were very hard on him. I've seen him before with a bowl full of ice to soak his wrist in at a signing.
If you do get the chance to meet him, try and think of something interesting or novel to say to him. If you happen to get him interested in something, he'll chat for ages.