As a British citizen, you have the right of abode in the UK, which means that you are allowed to enter and remain in the UK without any immigration restrictions. However, you will still need to prove your identity to the border officials. If you arrived at the UK border without any valid documents, it would be very difficult to prove your identity, and you could face delays and/or be detained until your identity is confirmed.

It is important to note that airlines would not allow you to board without a valid travel document, so you would need to obtain an emergency passport or alternative document from a UK embassy/consulate before traveling.