No you can't connect to a Service Bus Relay from AngularJS code since JavaScript only supports making Ajax calls through HTTP, where the Service Bus Relay communicates through a TCP connection without using HTTP.
You will need to write server-side code in your application that connects to and communicates to the WCF services through the Azure Service Bus Relay. Then you can expose whatever data and functionality you need to your AngularJS code by making Ajax calls from client-side AngularJS code to the server-side web application.
You have a Web Application that runs on the server anyway, so integrating this should not be an issue for you.
The layer and call stack outline would be:
AngularJS code calls back to Web App it's hosted within
Ajax call to Web App connects to Service Bus Relay
Service Bus Relay communicates with WCF service
WCF service handled method call and returns response
Service Bus Relay send WCF method response back to Web App
Web App returns Ajax response to AngularJS code
AngularJS receives Ajax response and does what it needs to as a result.
Additionally, if you could call the Service Bus Relay directly from the AngularJS / JavaScript code in your Web Application, you would still have cross-domain origin issues since the Service Bus Relay is hosted on a different domain than your Web Application.