If you agree to your blood pressure or blood sample results being sent to your GP, then she/he may use them in medical reports about you. For example, if you apply for a new life assurance policy, or for a new job. When people apply for new policies, insurance companies may ask if they can obtain a medical report from the GP. An insurance company cannot ask your GP for a medical report about you without your permission. Having given your permission, you then have the right to see the report before your GP sends it to the insurance company, and you can ask for the report to be amended if you consider it to be incorrect or misleading.
Your DNA samples cannot be used by lawyers or insurance companies, and will be used for research purposes only.