trouble with immigration on the way home?

has anyone had any problems when leaving the country, after having stayed a while?  i've been here two months...changed my tkt after arriving (orig for 3 wks)...and will probably be here approx another 2 months before going home and (if all goes well) applying for a fiancee visa to come back for good.  laying in bed last night thinking (always a bad idea), remembering that i will have to go through a bit of immigration in london b/f coming home, and am wondering if i will get hassle.

Don't see why you would.  They don't really keep tabs on when you leave unless you've been refused entry for some reason.  I extended my initial visit from 7 days to 10 days.  I'd say as long as you stay under the 6 month limit you should be fine.