This is the way I sorted out my last house, I rotovated the lot with a large
hired machine which went down about 18 inches. I then spent the whole
spring and summer withe the hoe, more or less every day was needed. The
only things I dug were the docks and dandelions which vanished after a month
or so.
Remember though this is time consuming and fairly hard work.
After this I treated the land as an allotment with a three year rotation
system, I was lucky to have access to lot's of cow manure which I composted
and then spead across the ground - I used a rotovator to mix it with the
soil. Weeds are always a problem so the hoe just has to keep working

Bob


just a word of warning. I think this is a good approach, but you must
make sure the soil is easy to dig, so you can easily pull up weeds as
they arrive (hire a rotivator when the soil is nice and dry if you
must). And you must be very thorough. It will be somewhat overwhelming
all those weeds that keep popping up over the springtime. So regular
weedings are a must.
unless you are sure you can till the whole 250sqm every week or so i
would cover half in plastic/carpet/whateveryoucangetyourhandson mulch
(or at least leave as grass - in preference of bindweed and other
serious nasties) until you get the other half under control.
sarah