The artwork is by Mike Collins who is a regular contributor to the Doctor Who Magazine comic strip as well as being known for numerous other comics work over the past three decades. You can see his website at http://www.freakhousegraphics.com
The retro style Doctor Who art has also been used on other merchandise. Some of which you can see here:
Really nice work from one of the best in the business. The Doctor Who calendar is published by Danilo Promotions and is available at many shops and calendar stalls at shopping centres etc. at £9.99. If you can't find one and need to order it, give your bookshop the ISBN 978-1-78054-583-7 for the UK, or ISBN 1-78054-583-5 for the USA.