Parky - my OH had knee problems for years, but didn't want to have op, until finally after a holiday where he was so restricted in what he could do, he decided to go for it. Both knees were so bad that surgeon suggested doing both at same time! They had him out of bed and walking with crutches the next day and the day after he was able to have a shower - the dressings are waterproof. I set up a bed downstairs for him, but he only slept there 1 or 2 nights, after that he could get up and down stairs.
It was painful for the first few weeks and the strong painkillers didn't suit him so he just took the max dose of paracetamol at the recommended intervals. Ice packs helped a lot - we always had some in freezer and some in use - sometimes I would have to go down in middle of night to replace them.
He didn't overdo exercises, but made a point of not sitting all day, but getting up and walking to kitchen if he needed something. He also tried to do his normal activities, like gardening. He went to a physio and got a loan of an exercise bike which helped. He found the Bonesmart site good.
After 3 months we were able to go on a holiday to France - plane, train and plenty of walking. He was still using one stick at this stage, which was a handy passport to getting to front of queues! But he abandoned it when we came home and knees continued to improve. He's never regretted having the op and it made a huge difference to his quality of life.
Best of luck for tomorrow.