The error message (An Error occurred when creating the shipment: SenderContact/Telephone may only contain digit and space characters) from Parcelforce is caused by the contact number field within your warehouse containing special characters, please follow the below to check this:
Click Warehouse then Manager Warehouses.
Click Edit against the affected warehouse.
Amend the contact number field by removing any special characters, only keeping numbers.
Save the change and then try generating shipment again.