The thinnest depth of TVs of a similar spec and age to this television is 17mm, the thickest is 100mm, and the average depth is 61mm. The 49UH661 has a quite thick depth (77.2 millimeters) compared to most of the other 4K and 8K TVs that were launched around the same time as this TV.
It may also be worth considering one of the other 77.2mm thick televisions currently available including the LG 49UH650 (£490) which is cheaper.
If you don't mind having a thicker depth then you might want to consider the Philips 43PUT6401 (77mm).
What does "depth" mean?