Excited for you😊
From my experience, if you buy a sorted car, the annual maintenance/upkeep really isn’t too expensive at all. Personally, I’d suggest you look for a car that’s been used regularly over a garage queen, as these cars prefer to be driven + with some history to back up regular specialist attention. But don’t worry about full service histories - these don’t seem to happen very often, if ever, with Lotus! Just some decent notes on upkeep in more recent years should be ok. Plus any owner who cherished their car will have kept paperwork.
There are some seriously excellent Esprit specialists out there, who are very reasonable IMHO - depending on where you’re based, people on here can point you in the right direction of a nearish one to you. And as someone who doesn’t know one end of a spanner from the other, I’ve always relied on specialists and simply get an annual service and MOT done on my cars - compared to classic Porsche, Merc and Jaguar experience, Esprit maintenance has always proved substantially cheaper + the level of care given is second to none.
Good luck with your search!