Would changing my network help my battery from draining to much?

I have the BB Curve 9300

I'm on 3UK (which requires it to be connected to a 3G network all the time).
I'm looking to using Virgin UK so I can use the phone on 2G networks.

I don't really use the phone for browsing, just a few emails/BBM/Texting and a few calls. (and I use it to listen to music sometimes).

My display is set at 10% and I have switched the LED Coverage Indicator off).

I've had this phone since the 25th of March.

What is your current battery life like?
Is it draining within 2 hours or 10 hours?

When I don't listen to music it lasts about 18 hours, with music playback (about a hours worth) it drops to 50%...

18 hours is very good for a blackberry, and yes, it will drop considerably.
This is all normal and changing network won't make a difference.

Many thanks... Would upgrading to OS 6 make a difference?

It may, as different OS's can improve battery life; that's a matter of trial and error.

ok, thanks.