prepare test enviroment for install service pack 2 in medium scale form

HI

In our organisation  has one sharepoint farm its build version is: 

Farm Information :
Configuration database version: 14.0.6029.1000  (i.e service pack1)

and this farm has

2 Webfront end servers

2 application servers and  2 Index servers 1 database server

so i want to upgrade to service pack 2,

 now daily  may users uploading documents to RBS storage of content databases in this forms web applications

so before install service pack 2 to this production enviornment , its better to try in test invironment?

if yes how i prepare test enviroment and how many servers i will prepare can anyone guide me in this

adil