Modify footer of slides

You can redefine the footline template as defined by the infolines outer theme (internally used by the Boadilla theme); \setbeamertemplate{navigation symbols}{} will remove tha navigation symbols:

\documentclass{beamer}
\usetheme{Boadilla}

\makeatother
\setbeamertemplate{footline}
{
  \leavevmode%
  \hbox{%
  \begin{beamercolorbox}[wd=.4\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
    \usebeamerfont{author in head/foot}\insertshortauthor
  \end{beamercolorbox}%
  \begin{beamercolorbox}[wd=.6\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
    \usebeamerfont{title in head/foot}\insertshorttitle\hspace*{3em}
    \insertframenumber{} / \inserttotalframenumber\hspace*{1ex}
  \end{beamercolorbox}}%
  \vskip0pt%
}
\makeatletter
\setbeamertemplate{navigation symbols}{}

\date{date}
\title[The title is quite quite quite quite quite quite long]{The title is quite quite quite quite quite quite long}
\author{My name}
\institute{My school}

\begin{document}

\begin{frame}
\maketitle
\end{frame}

\end{document}

You could change the outer theme and use one with two parts, such as the split theme. Load it after loading Boadilla. The second line is for removing the navigation symbols:

\useoutertheme{split}
\setbeamertemplate{navigation symbols}{}

(My school) is gone, date is gone, two parts. Perhaps you just like to adjust the color later, if you don't like the white on black color introduced by split.