I've been away for a few days, hence why I didn't answer anyone. Sorry! During the weekend my son used my laptop several times. He said he didn't have any problems with the wifi. It has booted up and connected immediately this morning too.
I had entered rfkill unblock wifi
in /etc/rc.local as Sezo suggested which appears to have solved the problem. Thank you all for your suggestions
Linux VGN-NS30E-S 3.2.0-49-generic #75-Ubuntu SMP Tue Jun 18 17:40:13 UTC 2013 i686 i686 i386 GNU/Linux
tanya@VGN-NS30E-S ~ $ X -version
X.Org X Server 1.11.3
Release Date: 2011-12-16
X Protocol Version 11, Revision 0
Build Operating System: Linux 2.6.42-37-generic i686 Ubuntu
Current Operating System: Linux VGN-NS30E-S 3.2.0-49-generic #75-Ubuntu SMP Tue Jun 18 17:40:13 UTC 2013 i686
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.2.0-49-generic root=UUID=ee6bf75d-fb15-4b29-8f12-1e85050f7904 ro quiet splash vt.handoff=7
Build Date: 11 April 2013 01:04:30PM
xorg-server 2:1.11.4-0ubuntu10.13 (For technical support please see http://www.ubuntu.com/support
Current version of pixman: 0.24.4
Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.