Book a return date but change it if needed. We’ve had to do this for numerous reasons... too many to list!
What I would recommend is booking for the LATEST you think you’ll return home. Though it won’t really matter so long as it’s not over 90 days. I suspect you’ll be limited by your work unless you are retired? You won’t be able to work (I know you know that but just adding).
Yes, work will be an issue. I have some annual leave built up, about a month, but after that it will be a problem.
Thank you for advising about booking a return date and then changing it if needed. This won't effect future travel to the US so long as it's within 90 days, right?
Also, is it possible to stay within the US for 90 days, return to the UK for say, a week, and then return to the US for another 90 days? I'm not sure if there is a cooling off period or anything but I want to make sure I have all options covered in case things take a turn for the worst.