Hello, I’m studying at one of the UK-based universities, and I was researching a

Hello,
I’m studying at one of the UK-based universities, and I was researching a subject about UK UK’s demolition and waste management. However, I could not reach enough resources to gather the data.
Firstly, my lecturer requested me to interview 10 experts on the subject after submitting my research proposal. However, I tried to reach 30 people in the UK’s demolition and waste management companies by message. However, I could only get a return from 2 people. But, since I could not collect enough data (this limitation should be mentioned in the limitations part), my lecturer asked me to do systematic literature research related to the interview questions. His request is to do research from at least 50 sources that have been published in the last ten years and insert the tables related to the interview questions. Afterwards, research should be completed in the light of those findings. In this case, the research proposal I shared with you needs to be revised according to the final document, and the dissertation needs to be completed with the existing research proposal. I would be grateful if you could help in this regard.
Ps: The sources are requested firstly from the UK and secondly from Europe. Particularly, Australia is not accepted.
The documents I shared in the attachment;
1) Existing research proposal
2) Interview questions and my findings
3) Example chart