If one of my grandparents were french what does that make me?

It "makes" you English with one French grandmother.

However, you are assuming too much: All folks of the British Isles (Scots, Irish, Welsh, English, and the rest) have French ancestry, Norman (which were Vikings that settled on the French coast) ancestry, Spanish, German, Netherlander, Scandinavian (remember the Vikings? That included Angles, Saxons, Jutes, etc.) and Phoenicians (Celts), as well as Africans.

Of course, Frenchmen have English, German, Netherlander, Spanish, Roman, African ancestry....

Your parents and yourself are born in England, making you British( if still in the UK) of English ethnicity with a French Grandparent...............

1/4 French, 3/4 British

It makes you English with some French ancestry. (If being born and raised in France made your grandmother French, then being born and raised in England makes you English.)

A person with French and English ancestry.

You are a citizen of the United Kingdom of English (75 percent) and French (25 percent) ancestry.

If you live in Britain, your parents are both British and your loyalty goes to Britain then by all standards you are British.

if your a uk citizen , your english

It probably makes you like nearly else (yes, including people of color) in the US, an American with European heritage.