You can email all of your documents up to Hull first - they will check them, and let you know if there are any issues before you go up. We did the trek up from Brighton as it’s apparently so much easier than dealing with London.
We got there late morning, and because we had emailed our docs up before, the whole thing took about 20 mins.
It’s not a bad train journey. Out of Kings X, then take a taxi from the station to the consulate.
As far as I know Hull is still open. Their website has recently been updated with 2018 opening times. Could be wrong but there’s a phone number on the website if you want to give them a call.
If you are doing this in CNX you need to have the bigger photos. There’s a shop that does them at Promenada next to the ticket queue. It’s disappointing to find this out when you get to the front of the queue and get sent away!