I've been speaking English since the age of 10, I've written two novels in French and two in English, and I've been teaching French and English for 22 years.
This means I have a clear understanding of the differences between the two languages and of the obstacles English-speaking students come across when learning French. That is why I specialise in teaching French to English speakers.
First thing first, despite what people say, English speakers are not bad at languages. What is bad, are the approach and methodology used at school.
French is a Latin language and English is an Anglo-Saxon language. This means that the roots are different and the languages operate in very different ways. Learning French is easier for Italian or Spanish speakers, because the roots are similar, as are many of the language points.
Overall, English speakers don't study grammar as much as they should at school, or not at all. And languages are taught with English as a constant reference point and translation as a key exercise, which is baffling, to say the least.
A translator is someone who knows both languages equally, which by definition, isn't the case of a language student. And even when you do know both languages equally, translation remains very hard.
As a result, and because of the inherent - yet entirely erroneous - belief that British speakers are bad at languages, it's hard for them to distance themselves from their own mother tongue in order to embrace a new language, a new pronunciation, and logical system.
What makes the learning harder is never French, ironically enough, but English! As I always say, using English to speak French is akin to squaring a circle. And my job is to prove this fact to them, often enough and as clearly as possible, so they stop reaching out to their mother tongue as a reflex and use what they know in French instead.
Using extremely concise structures and concepts from the English language, not to mention idioms or metaphors, does not help when learning French. In fact, 10 times out of 10, I will correct a mistake saying the following words 'this is English turned into French, not French. You didn't make a mistake because you don't understand or don't know the language point, but because you used English to speak French, which rarely works.'
My job is to get my students to leave English behind, while still feeling confident and in charge of their learning process. And by that, I do not mean getting them to stop thinking in English, but to stop formulating a sentence in English first and then translate it into French.
When they finally do, they invariably are surprised by how much easier it is to speak French, without English getting in the way! And how much less effort it takes, ironically enough.