Does the CLM license entitle to use IBM Websphere HTTP Server, IBM Websphere Customisation Toolbox and IBM Websphere Plugins ?

As stated "Each purchased client license for Collaborative Lifecycle Management includes a license to run one instance of WebSphere Application Server to support Collaborative Lifecycle Management."

Express editions of WebSphere Application Servers are also available for IBM i at no additional charge by ordering Web Enablement for IBM i.   Resource: Optional Programs

Websphere Application Server includes the following packages:
- IBM HTTP Server for WebSphere Application Server
- IBM WebSphere Application Server, Version
- Web Server Plug-ins for IBM WebSphere Application Server
- WebSphere Customization Toolbox, Version 8.0.0.0

So I would say yes.  The WAS license will entitle you to these products.

IBM Websphere HTTP Server
IBM Websphere Customisation Toolbox
IBM Websphere Plugins

The three products are part of the WebSphere Supplements download. They are covered by the WebSphere Base 8.5.5 entitlement.