We too are just outside catchment but do have one daughter currently at LGGS and one about to start in September. I believe the way the system works is that all girls with LA postcodes who pass the test are automatically offered a place then the remaining places are offered to those who live outside the catchment and also passed quite well. A key criterion is how far outside the catchment you are: if you are just over the line (as we are) then your chances are much better. I know there are several LGGS pupils from Garstang and Preston so it is by no means impossible to get in if you live that far away. We also suspect that they set the 'pass mark' of the test to make sure that they do have places available for those outside the catchment because they want to be able to offer places to the brightest girls irrespective of where they live.
Our advice for preparing for the test is to work with your daughter yourself. You know her the best of anyone and can give her the most attention. Some books we found particularly useful were the Bond series on "How to do 11+...". These cover the required syllabus in a simple way. There are also simple tests to assess what your daughter knows and doesn't know so you can then concentrate on the appropriate areas. We found that a lot of the syllabus had not yet been covered at school, so we had to do quite a lot of explaining. Closer to the date of the exam we got our girls (poor things) to do sample papers on their own, from various books, not timed at first then later timed. We saved the old LGGS papers until the end.
We also used a tutorial service, just a couple of hours twice a month from spring/summer of the year of the test. However we didn't rely on their assessments. We did talk to the school before entering for the test to get their opinion - we didn't want to put them through the hassle and stress (and it is stressful, for children AND parents) without knowing they had a decent chance.
We also made it as clear as we could that IT DIDN'T MATTER if they didn't pass! We'd love them just as much either way! And we didn't sign them up for it without their agreement to give it a go. And we promised them a special treat immediately after the test.
We have a younger daughter (aged
who might be doing the test in a few years if LGGS seems a good option for her. I think the only thing we would do different is to start working with her a little earlier. Probably a year before the test, just a couple of hours now and then. With the others we left it a bit late, which meant they probably felt a bit of pressure.
Hope this account of our experiences is some help. Good luck with it. We found it really rewarding doing 11+ study with our girls. And if they don't pass, or if they do and you don't take up an offer of a place, at least their Maths and English have had a good boost.