Define the company table before you import into it. (Don't use the "new table" option in the list of target tables when you import.)
Define your fields and specify "Unique values" and "Validate always" on your company field (or better yet a company ID field if you have such a column in your data to import). These settings will automatically filter out duplicate entries during the import.
it doesn't have a company ID field unfortunately but one will be created when i import. I will have to link contact_company with Company_company initially ? can I then run a get field value on my contact table and link via that after wards?
You would not use getfield() for that, but yes, you can link initially by company name and then use replace field contents to copy over an ID number from the company table to the contacts records linked to it before updating your relationships to match by ID instead of name.