hi, I had the same problem last month - I started checking for dates right after I passed my Life in the UK test on 12 July, and I couldn't book an appointment until 3 August, after weeks of increasingly obsessive checking. I also tried day and night, and just kept the window open on my browser while I worked so I could try at random times. The site repeatedly crashed and froze, and was worst right after midnight, in my experience. I suddenly got a range of open appointments at Sheffield in the morning on the 3 August, and was able to book easily. Very frustrating and stressful! Good luck!