The TEF is like the same as the IELTS. I had to write a newspaper article based on a headline they gave me and I had to write an article about it. Be smart and don't make to too difficult for yourselves (use easy tenses for instance, ...). I had to do a second writing part as well but can't remember what it was. It can be anything
The other parts of the TEF are quite similar to the IELTS. For the oral exam I had to convince a friend to buy solar panels. Reading was or very easy or quite difficult for some parts.
I thought I didn't do so well but had a nice score nevertheless. So if your French is quite good it shouldn't be a problem. Just think about the writing section to not make it too difficult for yourselves.
Good luck!