Question : Is Dallas Love Field (DAL) the cheapest airport for getting to London City Airport (LCY)?
Answer : Departing from Dallas Love Field is not the only way to get to London City Airport. Try looking for flights from Dallas/Fort Worth International Airport (DFW) as well. Over the next few months, flights from DFW to LCY are being priced 21% cheaper than flights from DAL to LCY. Being only 11 miles away, it's easily accessible for most.
Question : How long do most people visit London?
Answer : Of course you're not most people, but if you were, you'd stay roughly 15 days.