Hi Richard, as I understand it cribriform is a specific type of grade 4 prostate cancer which is a bit more aggressive than other types of grade 4. As John has said it doesn't really change your treatment except that, if you were a 3+4 and the 4 was cribriform, then this would probably rule out active surveillance which might otherwise have been an option. But as you are 4+3 you will probably need treatment anyway.
If you want to find out a bit more detail, (though you don't really need to) ,then here is a link to a video by Dr Scholz, an American expert whose videos are widely watched by member of this forum.
https://www.youtube.com/watch?v=-bgmkwpD4Zo
I only discovered that I had cribriform pattern from my pathology report after my prostatectomy, and I didn't really know what it meant for a long time. But that was more than 5 years ago, and I am still doing OK
Best wishes, Kevin