I'd say that if your DD is bright and you have a year to prepare, you should be fine if your DD is willing to put the work in.
DS1 is about to start at a super selective boys grammar next week. He's bright - not a genius - and also rather lazy sometimes, if he's honest.
I found out what type of exams were being sat for the 11+ at his school. They were different to the ones taken at many schools in 'Grammar Areas' (only one girls and one boys' grammar school round here, everywhere else is High Schools selective on the grounds of religion, siblings, distance from school etc. The 11+ here contained Maths, English (Comprehension) and English (Verbal Reasoning). They do not do the Non Verbal Reasoning tests. So that's the most important thing to check first of all. No point in your DD revising something like mad for a year when it's not even tested, or worse, not realising that something is tested when it is worth 30% of the marks!
I bought DS some practice tests (he did 3 or 4 I think) from the exam board, and we went through them together. He had a tutor once a week for six weeks before the 11+ test day, who did the same with him, had him doing similar exercises which developed the correct skills and she set him homework to do. That's it. I didn't make a huge thing of it, just explained that it always makes sense to practice when doing any sort of test or exam so that you don't get any nasty surprises on the day.
He passed fine and on the day he came out saying that it had gone exactly as he'd expected, even been a bit easier than he'd expected, as he had known the format and what was likely to come up.
He is a big reader though, which will have helped enormously with English Comprehension. He reads adult novels now, has done for a while, as well as teen novels. We've always had a dictionary by his bed and if he's ever asked for a definition of a word I've encouraged him to look it up. He has a good vocabulary which was commented on right from him being tiny. His natural talent isn't English though (must to my distress as I studied English Literature), he's a Maths lover and this is where his enthusiasm is generally.