So I've heard lots of things about nonreving to LHR... extra fees and taxes. (Airport tax?) Will it cost me buckets of money to go? I'm thinking about going for the weekend to see a friend. Ideas? Advice? Quit while I'm ahead?

I'm a newbie, so all advice is appreciated.

(So, right now, planning on leaving on a Th, returning on a Sun. Loads look great leaving from ATL, MSP, DTW on DL flights - my airline. And $$ looks nice too.)