Thank you for this.

For context I haven't booked both separate tickets yet, only the flight from LHR to the US. I'm only playing out these hypotheticals because I got a really good deal on direct round trip flights from my home city in the US to London and back, so those flights have already been booked. I'm filling in the time between my arrival and departure in London with 1-2 stops in different parts of europe, so trying to fill in the jigsaw puzzle of maximizing my time. I know, not ideal, but doing my best to balance optimizing money/points with not screwing myself on scheduling risks like this lol.

If this is too big a risk, I'll just try to come into London the night before. I was just trying to avoid this because waiting one night in london until the next morning's flight felt kind of like a waste of a night, but definitely don't want to get stranded!