Really, it should be a matter of minutes to do this. If you have large
movements to make it is often better to use the keyboard rather than
the mouse to move around - pressing the Page Down key a few times while
holding the Shift key down will take you to the bottom of several
hundred rows very quickly, even if there are gaps in that column - once
the data is highlighted in this way it is easy to click <copy or <cut
then move to the bottom of column B and press <Enter. A few
key-presses only.

If you need to repeat the process quite frequently then you could think
about recording a macro while you do it once, but ensure that you do so
with the Relative Address mode selected. Then in future you could just
re-run the macro - you won't get particularly efficient code by
recording the macro, but if it works then this may not be a great
concern for you.

Hope this helps.

Pete