As of my last knowledge update in January 2022, I don't have specific information about a school called "Grantham Preparatory International School" in the United Kingdom in my database. It's possible that the school you are inquiring about may have a different name, be a relatively new institution, or have limited publicly available information.

To obtain accurate and up-to-date information about Grantham Preparatory International School or any other school, I recommend the following:

1. Visit the Official Website: Check if Grantham Preparatory International School has an official website. School websites typically provide comprehensive information about their programs, curriculum, admissions procedures, and contact details.

2. Contact Educational Authorities: Reach out to the educational authorities or local government departments responsible for school registration and oversight in the relevant area. They can provide information about accredited schools in the region.

3. Local Directories: You can also check local school directories, educational guides, or directories provided by educational associations or councils in the area where you believe the school is located.

4. Contact the School: If you have specific questions about Grantham Preparatory International School, you may try contacting the school directly via email or phone to inquire about their programs, admissions procedures, and any other information you need.

Since my information might be outdated or limited, these steps should help you find the most accurate and current details about Grantham Preparatory International School or any other school you are interested in.