In my ToC, the "Bibliography" entry is treated as a chapter heading, so has no line of dots to the page number. However, as it has no sections, my publishers would like the line of dots. Same for the index.

What's the easiest way to do this?

Use the tocloft package, then where you want to switch it on

``````\addtocontents{toc}{%
\bfseries\protect\cftdotfill{\protect\cftdotsep}}}
\bibliography{your-bib-file}
\makeindex