They have been in decline in the area over the past few years, probably in part at least due to lack of suitable management. Although they should still be on the wing, you'll be lucky to manage a count into double figures.
Starvelarks Wood, which is 1 or 2 miles SE of the A127 / A129 junction has been the most reliable site in recent years, might be worth a try there as well.
The fritts were not out when I visited Starvelarks a week or so ago so hopefully they should be out now. they were also not out at Pound Wood. From my understaning only a few have been seen at Hockley and Belfairs Woods which is a dramatic downfall from the hundreds that could seen on the wing at any of these sites a few years ago.
I worry for the viability of these colonies so will be interested in knowing how many people have seen.
I saw some at Belfairs this afternoon, all were quite fresh so will be on the wing for a little while yet. Had a wander around Starvelarks too, but didn't see anything, it all looks a bit overgrown..:-C