One of my best friends does arc and anth and I lived down the corridor from her last year, she seemed to do less work than the historians, but had the same amount of written work, one essay one week, two the next, alternating each week. However every few weeks she just had to do a presentation, which looked like a lot of fun! I'd say Oxford workload is fairly standard with all arts subjets having roughly the same number of essays, how long they take you/how many hours you work per day depends entirely on how quickly, how much, and how efficiently you read.
On the subject of fieldwork, she's going to have barely been home all summer, with a dig near oxford right after term, then one down in devon, then several weeks in tanzania.
Again like all arts subjects at least, there is no typical day. Your time is your own, with few lectures, few to no labs (although arc and anth have a few throughout the year) so it depends entirely on how you like to work, if you like to do two full days before an essay is due, or work a little each day throughout the week.
Good luck.