I did well in my GCSEs and my biggest tip is make a revision timetable, ideally from the first week in september and stick with it - if it's too much and you're not getting it done and thinking you might burn out, reduce the number of hours, 9 months of weekly revision will amount to a lot.
Secondly, find revision methods that work for you, personally I found flashcards super useful (but just make sure you review them) and I really loved the anki app for them
In terms of summer revision, I personally would say it really isn't necessary, even for top grades but if you really want to do some, I'd say just have a look over and refresh your knowledge of topics you're weaker on but most importantly make sure you have a break and feel well rested and prepared for the year - I know a lot of schools have lots of assessments and the beginning of Y11 so you'll get an opportunity to do some revision then (but don't worry if you do poorly, you have a couple of weeks to revise for 8-12 assessments, most, most people do SIGNIFICANTLY better in their actual exams)
For past paper, I personally would save them until the exam period and April, just because at that point you hopefully should have revised everything and the papers will be most useful to you, and for your mocks to simulate the real exams as much as possible you won't want to have seen the questions (which will be past paper questions) before - you'll thank yourself for this in May
For English (and any subject) it absolutely is possible to move up 2+ grades - I got a 5 in my November English lang mock but a 9 in the real thing - all I did was practice one past paper under exam conditions, make sure I knew how much time to spend on each question and look at the examiners report for the past paper I did.