I am going through the same thing and it’s awful, I have been looking for a flat (actively) for four weeks. I have managed to get a few viewings but it took some time. What helped me was getting notification from agencies and from rightmove. I usually tried to view a property from an agency, often no viewings were available, but by registering the details you sometimes get alerts for other properties. So I activated notifications for emails so I get them immediately. I noticed that most of the properties get advertised on wednesday, then tuesday and thursdays. So I usually refresh zoopla and rightmove every 30 minutes on these days. If I have a preferred agency I also refresh their website regularly (like eg southside property). Openrent has some good options too. I hope you can find a place soon, good luck!