This is assuming you are using Lr6 as you didn't say.
If you use the GRID, SQUARE or TRACK galleries you can use the "Gallery Author URL" to return to your main web site although the return dialog gets a "by" placed in the text which is a poor design. If you wanted "by" in the text you could place in in the "Gallery Author" field yourself. This could probably be changed to not put the "by" in easily in the Lightroom templates. See here.
If you use the CLASSIC gallery you can use either the Contact Info or Identity Plate "Web or Mail Link" to return to your main web site. I have done this on my site here. http://www.ajaxmtn.com/
Take a look at this thread. There are several Ideas. I like the idea in post #14