Hi, I know this is long and I don't know if it'll help but here's my experience.
Background: I'm 39, have friends in the UK and elsewhere in Europe, got sick of my job and needed a break last year. Friends in Exeter offered to host me for a 6 month stay. I took a leave of absence from my job, cashed out some stock and bought a plane ticket. I took with me a letter from my employer stating that when I returned I would have employment, copies of my current bank statements, copy of my return flight info, front page of my apartment lease (which I subletted while away), and phone numbers of various friends in the UK whom I planned to visit.
The conversation with the IO went generally like this (while he perused my passport):
IO: Hi, what's the purpose of your visit?
Me: Visiting friends and doing some traveling.
IO: How long are you staying?
Me: Staying here for a few weeks, then going to Ireland and later to Germany and Switzerland, then back here. I have copies of my itineraries if you'd like to see them.
IO: I see you were here last August, why was that?
Me: Visiting the same friends for a couple of weeks.
IO: How can you be away from your job for so long?
Me: I have been with the company for over 10 years... they owe me some time away. I have a letter from my employer if you'd like to see it.
IO: How much money do you have access to?
Me: About $5000.
IO: Are you aware that you cannot work while here as a visitor?
Me: Yes, not wanting to work for a while is the main reason I'm here.
IO: Where are you staying while you're here?
Me: With friends in Exeter, also some others in the London area.
IO: Where did you meet them?
Me: Online, a couple of years ago.
IO: Have you met them in person before?
Me: Yes, that's why I was visiting last summer for a couple of weeks.
IO: And when do you plan to return to the US?
Me: In the early autumn. My brother and sister-in-law are due to have a baby in October and my mother will kill me if I'm not there for that.
I do have my itinerary and ticket receipt printed out if you'd like to see it.
IO: (laughing) Well, based on your travel history, preparedness, and the fact that you don't seem to be the young, irresponsible type we worry about, I'm going to let you in. Have a good visit. (Was he saying I'm old?!
)
He didn't even ask for any of my documentation (other than passport) but I had it all in my hand luggage just in case. I will say, however, that when I came back from traveling mid-summer, the IO gave me the same drill but advised that I shouldn't leave again before it's time to go home. He said, "I am okay with letting you in, but others might question your coming and going so much." I thanked him profusely and moved on along. I left two weeks before my actual 6-month deadline (though technically I had a 3 week cushion from being out of the UK on my side trip).
Hope this helps. I was a little nervous, more so the second time actually, but I had everything I thought they might need printed out and wasn't evasive about anything. I think what helped the most was being completely honest. I knew going into it that they would be concerned about a single American woman wanting to enter the country for six months. But I was confident in my answers because I didn't have anything to hide.
Good luck!