Quote: "So for example your walls you could just simply draw them in place rather then moving them around hoping they would fit nicely together."
Quote: "I have sat for ages placing damn fences down lol and re going over them all after running a test to see if they are placed right..."
Press 'b' once to snap objects together(using small increments), twice to use full grid snap, of course snap will depend on grid alignment and entity scale (100"X100, 200"X200" etc") and you should start using snap before placing the first object. It may be that you'll find unless your entity's are equivalent grid scales this wont work as well as you would like, but I always have made walls etc to these scales so cant say for sure. The main problem with this will be placing objects higher up, you dont have a vertical grid so have to raise objects by eye...for now at least.