I had a hip replacement last May, just before I was 80. I convinced myself that I would be marching down the street in a matter of weeks. The reality was a lot more pain than I expected, especially getting in and out of bed. However I could cope with the stairs after a few days, and by the end of 6 weeks the pain had considerably lessened, I was driving again and walking well, with a walking stick. I am now feeling very fit, and have also managed to take off 30lbs, which is a big help in keeping mobile. The hospital will probably assess you and lend you any aids that you need. A toilet frame is particularly useful.
I found that having a small wheeled walker upstairs and down helped a lot with getting about in the early days, and a small pillow between my knees, in bed, eased the pain. I was instructed to sleep on my back and wear elastic stockings for six weeks after the op, both very uncomfortable, but necessary.
The first couple of months were not easy for me, but some people seem to recover more quickly. Some also take longer, never get back to complete mobility, or end up with one leg slightly longer than the other. In spite of the potential pitfalls, most people never regret having the replacement. I was in a great deal of pain previously, and have been given back my life!