Is it possible to turn off the e-mail part of the unit for use as a
phone only, out of work hours and weekends?

Hello g4pei,

Thank you for your question. 

You should be able to turn your phone to email-only by going into your
profile and changing the profile to "Phone Only".

You could change it each time you want this to occur, or you could
create a new profile and just switch profiles when you want to go into
a mode without email.

Sources:

Blackberry Forums
http://blackberryforums.pinstack.com/3430-how_do_i_turn_off_my.html

Blackberry Forums
http://blackberryforums.pinstack.com/7833-how_do_i_turn_off_email.html

Search terms:
BlackBerry 7100v "turn off email"
blackberry turn off email
BlackBerry 7100v "phone only"

If you need any additional clarification, let me know and I'll be glad
to assist you.

--keystroke-ga

This site may help with this answer and may others you might have www.pinstack.com 

Lots of nice people and great hint tips etc.

Havn't found the answer (if indeed there is one) but nevertheless, a
great BlackBerry site. Thank you.