I have read that 328P chips come set-up as 3.3v & 8MHz ready from factory?
It comes set to use the internal 8MHz oscillator and a pre-scaler of 8 so the factory operating frequency is 1 MHz.
The "Speed Grade" chart in the datasheet shows three data points:
4 MHz and 1.8V
10 MHz at 2.7V
20 MHz at 4.5V
"Maximum Frequency vs. VCC curve is linear between 1.8V < VCC < 2.7V and between 2.7V < VCC < 4.5V."
3.0V is plenty to run at 8 MHz since 2.7V is enough for 10 MHz.
You will either need an 8 MHz bootloader or you will need to run a 16 MHz bootloader at half the baud rate.
You should probably include an ICSP header, unless you plan to program the bootloader BEFORE you solder the SMD processor in place. If you have an ICSP header and an ISP device you don't really need a bootloader. You can get a nice USBasp ISP device for less than $5 via eBay.