Live Chat – Where to Place Button on a Customer Service Portal

Short background is that we're working with a self service portal. The home page will feature a call-to-action of a search form for their queries e.g. "What is the flexi time policy"

Below this there will be top 10 lists of newly added FAQs, most popular and relevant sections.

Once a search has been done, the results will be appear and going into one of the results will present the user with a knowledge-base article and/or a FAQ.

In addition we will have forms the user fills out e.g. a flexi leave form. We will have FAQs listed along with examples

We will be introducing a web chat feature. My question is considering that the whole site is based around self service, FAQs and knowledgebases, should the "Web Chat" option be available on each and every page or should it be present once a search has been made or more wider than that, when they're not on the home page, based on the fact we want them to find the information themselves first?

I have reviewed other similar questions but none seem to be around a website dedicated to help/support that encourages users to self-serve.

Example of websites that will be close to what we will have:

Thanks