aurel2108, you think like a French, and you shouldn't when you try to write in English.
When you try to say something in English, make it simple. You don't need a very complicated sentence like in French. because "I've got a little level in English" fells quite weird, I've never heard that.
So I think that you could say "My English is bad, so excuse me in advance" (and yes, it's "advance", not "advense", that doesn't mean anything)
I think too it's a good idea to create this topic to help each other to speak a good English. Once a time I talked everyday with a friend who talked only in English (she wasn't French), and that was a very good training for me
Well, I don't say that my English is perfect, far of that, but it's quite easy for me to understand and write it.
So I hope I can help some of you, and maybe I will learn things too
If you found any mistake in my post, please tell me