Can anyone tell me please how, when I send / forward an email to a number of people from my address book, I can send it without the recipients seeing who else i've sent it to ( Hope this makes sense ).
Yep. To do this you need to put the people in the BCC (Blind Carbon Copy) part of the "To".
This is the same kind of tricks that spammers use to protect their lists. Choose one random one for the "To" maybe even your own email, then put the others in BCC
If you don't want any of the other recipients to any of the others' addresses, send the message to yourself (in the main To: box) and then do as squarebear says.