Would I be better off with this
or this
then?
They look to be the 328P type so should be the same as the chip in an Uno. That one from farnell looks a bit odd though, the data sheet seems normal enough but the image shows it to be rather wider than usual PDIP chips, and there isn't anything on the webpage itself which explicitly mentions pin spacing or width of the device. The datasheet talks of pin spacing and seems to say it is as usual, but for all I know farnell might have taken a standard datasheet for the atmega328p and accidentally put it on the page for a 328p in a wider format.