Nice sandy beach with a big meadow next to it. An alternative during summer is the access at the surf school, about 200m east of the bridge to the Badeinsel. This access has no beach, just grass and footbridges between tehe boats.
From Hanover drive west and get to Wunstorf and from here northwest to Steinhude. Here drive to the Badeinsel or 200m east of the footbridge the surf school.
During summer (May 15th to September 15h) surfing is forbidden and the beach reserved for beach goers. And the lake is closed for surfing from November 1st to March 31st. This leaves only a short period to surf on the Badeinsel. But during summer you can also access the lake via the surf school.