Begin by accessing your Google Cloud Storage to identify and download the data you need. Use the Google Cloud Console or `gsutil` command-line tool to download data files from your GCS bucket to your local environment. Example command:
```
gsutil cp gs://your-bucket-name/your-file.csv /local/path/your-file.csv
```

Set up a local environment where you can process and transform your data into a format suitable for Teradata. Ensure you have sufficient storage and necessary tools like Python, CSV utilities, or any scripting language you prefer to manipulate files.

Use a scripting language like Python to process and convert your data into a Teradata-compatible format, typically CSV or text files with appropriate delimiters. Ensure data types and formats align with Teradata's requirements. For example, dates should be in `YYYY-MM-DD` format.

Install Teradata SQL Assistant or BTEQ on your local machine to facilitate the data loading process. These tools will allow you to execute Teradata SQL scripts and load data files directly into your Teradata database.

Before loading the data, create the necessary tables in your Teradata database that match the structure of your data files. Use Teradata SQL Assistant or BTEQ to execute SQL `CREATE TABLE` statements to define the schema.

Use Teradata BTEQ or FastLoad utilities to load the transformed data files into your Teradata tables. These tools allow batch loading of large datasets efficiently. For BTEQ, an example script might look like this:
```
.LOGON your_teradata_server/username,password;
.IMPORT DATA FILE=/local/path/your-file.csv;
.SET RECORDMODE OFF;
.SET WIDTH 65531;
.SET FORMAT OFF;
USING (column1 INTEGER, column2 VARCHAR(100), ...) INSERT INTO your_table (column1, column2, ...)
VALUES (:column1, :column2, ...);
.LOGOFF;
```

After the data load completes, verify the integrity and quality of the data in Teradata. Run SQL queries to check row counts, data types, and sample data to ensure the migration was successful and the data is accurately represented.
By following these steps, you can successfully move data from Google Cloud Storage to Teradata without relying on third-party connectors or integrations.