I understand. But I have been asked to provide tax residence certificate, utility bills, flight tickets, rental contracts of my new country.It's spelled backpacker and I don't understand at all what you are trying to say.
You can have a look at the UK tax residency flowchart:
https://assets.kpmg.com/content/dam/kpmg/pdf/2016/01/statutory-residence-test-flowchart.pdf
You will see there is no "lives in cheap hostels and has bad hygiene" criterion for tax residency.
If you don't fulfill the criteria for tax residency, you are not a tax resident in the UK. You can't be.
You are making stuff up. Most countries ask for a new address. Very, very few countries will ask you to prove that you have a new tax residency.
You don't seem to understand the meaning of the terms "both Contracting States" and "double taxation".
Just FYI
When you have investigation is different reality. They can say - we don't believe you are real emigrant and you can fight it in the same government court