Hi I am looking for the best resources for either online tennis
lessons, tips etc or someone to recommend an excellent book which
would help improve my technique.

I have had a look on amazon and there are thousands of books to choose
from - so I was hoping someone could recommend the best one!

I am a club level player.

Thanks

Insh

This one has been continuously in print for more than 30 years:

Amazon.com: The Inner Game of Tennis, by W. Timothy Gallwey
http://www.amazon.com/exec/obidos/tg/detail/-/0679778314/qid=1114283288/sr=1-2/ref=sr_1_2/102-4777296-4068902?v=glance&s=books


I read it when it first came out, and I found it to be very useful (I
am also a club level player).  As the title suggests, it deals
primarily with the mental aspects of the game, and for some of us,
that is where we need the most advice and practice.