The client should be responsible for the collection and verification of the data. You can help by designing forms, testing consistency selecting samples etc. Send the client the data you have and ask them to verify its correctness saying that if you do not hear form them in 4 days, you will continue, assuming the data are correct. You could hire folks for data entry but you cannot assume responsibility for supervision when others are better qualified. Very few patients need a heart transplant.
All patients deserve a competent doctor.
Similarly most statistical analysis you will do will involve only t-tests or sign tests. This is good. Your skill we be shown in reducing a complex problem to such a test. The simpler the form of analysis, the more convincing should be the result. Statistical components of projects.