I only have experience of the Goswell Road one and it’s about what you’d expect really. Show up, pick a number and take a seat. It was pretty busy but there was the odd seat to be had. I think the wait to submit was about 2 and a half hours and later on in the week the wait to collect was a couple of hours as well. This was all in the midst of an apparent IT failure that they said was slowing things down (the regulars in the crowd didn’t seem to think this was much of a surprise!). Once at the desk it took about 5 minutes to check everything and be on my way, though there are always people with seemingly ‘complicated’ situations in front of you that take ages.

While waiting I saw quite a few agents arrive and swan straight up to the desk with a folder full of applications, so they obviously have some kind of priority arrangement.