What country, I sometimes do office layouts, and so far havnt come a cropper with any regs, I allow 1m min for access ways (access being defined as anywhere more than one person will pass through, try to leave 1m everywhere, but will drop below to about 800 for single user access), Push back I use whatever feels comfortable, trying to match up with standard unit widths so as to avoid unsightly gaps, ie I push the gap out a bit to the next unit width rather than closing too far. What the UK regs reccomend I am not too sure, but the 1m thing is a fixed access width AFAIK.