There is a CAA run scheme to help return lost drones to their owners called ‘drones reunited’, however you have to have registered your drone with the CAA to use it. If you have, then you may find their website helpful.
There are also other ways in which you can try to locate your drone:
Firstly, have a look around the Facebook groups local to your area in case anyone has posted about it, and if they haven’t then you can put out a post asking if anyone has found it.
You can also put up posters offering a reward if someone finds your drone and returns it to you (assuming you get the appropriate permissions).
There are also several lost and found schemes across the UK, one of which is the Metropolitan Police Lost and Found scheme.
If this is the S49 you posted about, it may have flown for a few minutes after it started to fly away (assuming you had already run down the battery a bit). You can look on Google Maps and form a search pattern to cover the area around where you lost your quad - if you can remember the direction it flew then that is especially helpful.
Finally, try to learn from the flyaway to make sure it never happens again. Many environmental factors, such as power lines, can disrupt your control of the aircraft, so always scout where you are going to fly to make sure it is safe to do so. I also put my contact details and the phrase ‘reward if found’ on my drone so if it is lost, the finder can easily contact me to return it.