I have come to the UK in the course of fleeing my abusive family and thus ata time in my life which was quite uncertain, unclear, and precarious. As my family is already an expat one (Americans living abroad in the third world), I had no definite ties to anywhere in the world including the US and not much of a clear life trajectory, either. When I landed in London my understanding was that as an American I would be allowed to stay as a visitor but not to work for 6 months. On my entry card I wrote 6 months as my intended departure date, thinking that this wouldn't be a problem, but I had no clear forward plans. As a result of my murky life circumstances and unexceptional finances, I was denied entry at the border, and flown back to the US where I'd already given up my room and had no place to stay.
I got a bed in a hostel and contacted the British embassy to see if I could get any kind of explicit visa in advance of traveling, or how I otherwise could enter the country. I was told repeatedly that since I was an American, I didn't need a visa and thus was not eligible for a visa to enter, but when I asked them what of my previous denial if entry they said that that was their only advice that was available.
I rang around to some British law firms in the US, and they quoted me like $1000/hour for advice but said the same, that I didn't need any visa to get in.
I soon gave up and got a cheap flight to Ireland. There i spoke to the local UK embassy with no other insights but to just try my luck at the border and see how it goes. I got a sail-rail ticket through Scotland and onto London. In Scotland an official uniformed UK border agent asked me for ID, I held out my US passport card, he briefly squinted at it in the corridor without recording anything, and waved me through saying thank you.
I was quite traumatized by family abuse and took a while to find my bearings during which I forgot about looking into my visa status. I have tried to find help in possibly claiming asylum because I don't really feel safe in the US or where I grew up as my family are connected with authorities in both places, but that has led nowhere and I'm ready to give up. In the three years since that time I have developed some roots and life here, and also lost my passport card, left with a passport that contains an ugly stamp indicating my previous refusal of entry to the UK. Meanwhile I have (decent) family in the US that has invited me to visit who I might not have that many more chances to see. I'm pretty worn out from being completely on my own over here for these years and could really use the rest, so I might actually go.
My passport should be coming up for renewal soon, anyway, so if I simply apply for a new one once I'm back in the US again, then it won't have that ugly denial of entry stamp and I could presumably just enter as any other American would, especially since I'm in a better position now financially. I also have some ideas about how I could convert that into some more lasting types of visa to stay even longer.
I gather that the UK does have immigration checks upon exiting the border at airports, and I imagine some awkward questions if I pass through there on my old passport. What consequences could there be here? I'm most worried that I could be explicitly and unequivocally notified that I'm officially banned from the UK. I don't think that would ruin my chances of being granted once again discretionary entry in the future if I had a fresh new passport and more favorable financial circumstances that are demonstrable, but if I've been explicitly and unmistakably informed that I'm no longer allowed in, then it could be awkward if I enter again and have to fill out forms.
But could these awkward conversations likely be avoided by leaving through, let's say either Ireland via the ferry, or by France or Holland via the train and attempting to travel simply on my driver licence until I must fly across the Atlantic?
Which of these options would be the least stressful in terms of time effort and distance?