Start with bookstores. In the UK:
Methven’s – my local bookstore.
Murder One – crime books.
Goldsboro Books – great guys. First editions.
madaboutbooks.com – my publisher, Hodder & Stoughton
In North America:
amazon.ca – yes, Canada has the books, and sells them!
Chapters-Indigo – Canadian chain, also selling them!
Also available in bookstores around our planet – they’ve been sighted in Borders and other stores in Singapore, Hong Kong, Malaysia, Australia, New Zealand, South Africa, Tanzania, Norway, Switzerland and Austria.
Let me know if you catch any.