I've had a quick peek at OCR Unit 1, it looks similar in style to the EdExcel syllabus with much overlapping content, but certain questions can be more involved than EdExcel (I'm used to model diagrams, as opposed to labelled pictures for example. I've never seen a question involving moments calculations in EdExcel, or describing GPS triangulation before).
It's perfectly possible for you to do well on OCR, but EdExcel physics is a bit easier. A majority of institutions (including RG), except the most competitive (Oxbridge and maybe two other Universities) won't care about the fact that it's not OCR.
I'm not sure about your practicals situation though, I've completed EdExcel AS/A2 on legacy and I've definitely had some.