Welcome Ecoboy and to the many new Irish visitors.
I wish I could give a precise formula but differences between weeds and soil make it difficult. Chapter 5 in my Course book is devoted to this and I could write a whole book on the subject. Also Chapter 6 on weeds is important because the precise course of mulching depends what is there. What are your pernicious weeds?
For example if there is just a small amount of couch grass and other traditional suspects, I would not do any initial clearing before mulching.
If soil is poor I would aim for an initial four inch mulch of compost/manure. That would kill almost all weeds except some perennials, which could be tidied up with a trowel as they poke through after two or three months. You could plant into this mulch, through spring and summer. But if there are many perennials with big old roots, I would consider a sheet of black polythene on top of the compost.
If using black plastic, just an inch or two of black stuff under it will improve soil which is already in a state of reasonable fertility (eg the grass is abundant!).
So it depends on many things, also how much manure or compost you can find or afford. I would do it in stages, say a quarter of your plot at a time. Then you can assess which precise method is best for your land.
At the end of a year you should have really clean soil with almost no perennials and with little desire to grow annual weeds. There is also a post in these forums about growing potatoes in a clearing year, through holes in black polythene.