On many keyboards, the <Alt> key acts as <Meta>, so try it.
Instead of typing M-a, you can type
<ESC> a. In fact, Emacs converts M-a
internally into <ESC> a anyway (depending on the
value of meta-prefix-char). Note that you press
<Meta> and <a> together, but with <ESC>, you
press <ESC>, release it, and then press <a>.