OK, there's still some information missing here, but I'll take a stab at an overall grade for you.
I know you have "i have 8 distinctions, 3 merits, 1 pass and 1 near pass" and I know what you're grades for units 1 through 4 are. However, I asked above, "For those units assessed by examination (that's units 1, 2, 3 and 4), what unit points did you attain?" That is very important as it can make a huge difference. As you haven't answered that question, I'm going to have to give you a range of overall grades.
In unit 1, to get a merit you must have had at least 15 points, but not more than 23.
In unit 2, to get a merit you must have had at least 20 points, but not more than 31.
In unit 3, to get a pass you must have had at least 12 points, but not more than 12.
In unit 4, to get a near pass you must have had at least 8 points, but not more than 11.
That leaves 9 units which I know are all distinctions except one, which is a merit. You haven't told me which one - this
could make a difference.
If we take a worse case scenario and assume you have the minimum possible points to attain each of the grades you received in units 1 through 4, and we assume that the remaining merit was in unit 5 (which is larger than most of the remaining units), then your overall grade is DDM.

However, if we take a best case scenario and assume you have the maximum possible points to attain each of the grades you received in units 1 through 4, and we assume that the remaining merit was in unit 6 (which is smaller than unit 5), then your overall grade is D*DD.

Unless you can tell me the
points you have received for units 1 through 4, and you can tell which which of the internal (coursework-based) units you got the merit in, the best I can give you is the above range:
somewhere between DDM and D*DD.
Note for the optional units above I've just picked any because it doesn't make any difference and because, despite me asking "Which unit was each of those grades was in" you haven't told me.