The new series of New Tricks is due to air in September.
Looking at Digiguide the first episode will air 10th September, as Simon said his was the second episode so it should air on the 17th September 2010, unless they’ve changed the running order.
Edit: Simon has said his role is very small.
Update 17/09: Simon’s episode will be 8th October, so a little bit more of a wait: http://www.bbc.co.uk/pressoffice/proginfo/tv/2010/wk40/fri.shtml#fri_tricks
If you want to discuss this you can on our forums: http://www.simonmaccorkindale.net/forum/viewtopic.php?f=49&t=955