You are looking for a nano container in an urban area. Muggles will pass by quite frequently, but you should find the space to retrieve this cache without being bothered too much. There is a corner shop nearby.
At the GZ you will find yourself in "The Lakes Road", which is a bit bizarre as it's uphill (from Bewdley town) and there isn't a lake in sight. (There must be a reason, and if I ever get to the bottom of this I'll add it as an amendment.) There's quite a nice view of Trimpley hill from the GZ, too. If it's not a C&D you're doing, there's a pleasant walk from GZ along the lane adjacent to the shop, which goes down to the disused railway line and Bewdley Brook. If you turn right onto the old railway track, which will take you to the Button Oak road, where, if you turn right, cross the road after say about 50 metres (and take care here), then take the track to the left, you will pretty soon reach the river (Severn!), where you might wish to turn right and follow the riverside into Bewdley, and then walk (or bus!) uphill back to the GZ. (Far fewer buses on Sundays though.) Allow a little over an hour for this.
There is ad-hoc parking around the GZ area.
Remember, it's a nano, so don't forget your pen/pencil.
Congratulations to Dobunnis - FTF and to The Senior Crabbes - 2TF