I have the privilege of knowing many "non English " people and i have to say that their English grammar and speech is technically alot better than the average kid[child] born native in this country.Thank god for spell check LOL
Our language is so variant from one small area to another , a matter of miles for example a native from Essex will sound different from someone in Cambridgeshire 50 miles apart and the person from Cambridgeshire will sound totally different to someone from Norfolk,Suffolk also only a handful of miles apart.
Ironically you would probably learn better English from a Dutch person or someone from a Scandinavian country that is fluent in the correct English.