Hi Rosie, welcome to IIS
First up, nice shots
Only a couple of problems.....firstly, nuke that light!!!!!
. Or find somewhere you can take piccies from that's not got too much light in it. You may need to drive to a reasonably dark location.Secondly, you'll need to up your ISO to at least 800 to be able to gather enough light to image the comet. Now it's getting dimmer, I'd suggest at least ISO1600 and 50 sec exposures or longer. Your F stop is fine, but if you can lower it, then do so. 16mm will give you a nice wide shot
You really need to be setup and ready to shoot at around 3am....3:30 at the latest. I would even aim to be ready by 2:30am. The comet is higher up now, but being dimmer, the less light you have to contend with, the better.