You could attempt to change Windows Update service to automatic start by editing the Registry. You can ignore this post if you're not familiar with editing the Registry.
The registry value that determines the start type for Windows Update Service (wuauserv.exe) is located here:
REG_DWORD value for automatic start = 2
Disabled = 4
Your current value for Start is probably 4 (disabled). Change it to 2 then go and open the Services window and check the startup type for Windows Update. If the Services