My friend, you still have S5 and S6 to complete!
In Scotland, universities tend to care more about your Higher results rather than your National 5 results.
If you're trying to get into an English uni (which you are as you say), then you want to complete your Advanced Highers.
You can view the entry requirements for your course and they will tell you which qualifications you need.
I know many people who haven't gotten the greatest grades for National 5 but have managed to do well on their Higher exams which allowed them to get into their chosen courses at prestigious unis such as St. Andrews and Edinburgh.
If I were you, I would gather your thoughts and think about what you're going to do for S5. Plan out your chosen subjects and lock in. Get some work experience (help out at pharmacies, etc). I'm not sure how you can plagiarise a folio accidentally but don't do it again. Don't overestimate yourself because these exams don't care whether you displayed "early signs of intelligence" or not. Most importantly, don't get too bothered by these results. It is all in the past now. You have to focus on what's next or else you will fall even further behind.
Congratulations on the 4 As!