How to overcome "Add new date link" issues in the 7.x-3.4 Calendar?
OK, so I have fixed this with a custom work around. There are many modules that I am using that may be interfering with the permissions to add a new date, and be limiting what can be displayed in the view. No matter, here is how I solved it:

First of all, set up the modules and permissions as following:

Go to admin > modules, and find the PHP Filter module, ensure it is enabled:


Next, go into the permissions and find the following:


Ensure that the last option, "Administrator", is selected.

Next, go to the view where you would like to add the "Create Booking" (or whatever content type it is you are after.) From here, create a new header of type "Global: Text area"


What I chose to do next was create a link to a new view, and on this view I expose the form to add the new date/event. If you want to embed the create form here, then skip the next step, however I find doing it this way leaves the current calendar in it's original state, and by clicking the about to be created "+ Add Event" link, you will be taken to a new view that contains the calendar and the exposed form.

Now, select "Full HTML" as the Text format, and place the following code in the text box. This will create a link to a new view, which we will make next. The two lines below are simply coloured text that I will use as a legend for the calendar.


&lt;a href="/calendar/create_booking"&gt;+ Create Booking&lt;/a&gt;


When we next create the view containing the form to add the new date/event, if you chose to use a different path, come back here and change "/calendar/create_booking" to your preferred path.

Now, apply changes and save the view. Go back to your Admin > Structure > Views page, and locate the view of your current calendar. Now, on the "Operations" dropdown, select "Clone View"



Rename the newly created view (I called mine "Create {Your Old View Name Here}"). Now, open up the "Edit" option for this view and create a new Header of type "Global Text Area" as before. This time, we want the Text Format to be "PHP Code" and to place the following code in your text area:



&lt;?php 
  module_load_include('inc', 'node', 'node.pages');
  $node_form = node_add('node_type');
  print drupal_render($node_form);
?&gt;


Remember to change 'node_type' to your desired content type. Save the Header, and return to the last screen. Now simply change your path to what you wish:



And now finally, go back to your original Calendar view, edit the header to contain the correct path in the link we made, and you're finished! The form is now exposed for users to create a new event/date. Ensure that you set the appropriate permissions for users to be able to create this content type, and remember that their view of the create form will be much simpler than yours.

Hope this helped you if you had the same issue as me!