When I did supply last year, I got paid for 6.5 hours per day. I think the rate was £21 per hour. The 6.5 hours was basically five lessons plus breaks. I did not have to do registrations, and if I did, I got paid extra.
Supply rates basically include holiday pay, so they are slightly higher than the hourly rate for a regular teacher's directed time.
Supply teachers walk out at the end of the day, so there is no work to do at home. Last year I did supply in one school and a two month contract in another in the same LEA. The contract work was much harder as I had to do all my P&P in my own time. I thought I had made a bad choice by accepting the contract position, but the advantage was knowing that I had fulltime work, getting CPD, and the all important reference.
In my current job (permanent), I do very little at home. I don't like bringing books home in case I forget them, or the dog eats them . The type of stuff I will do at home is to hunt the internet for little snippets (not essential to lessons, and can be done while I am watching Eastenders).
I do try to arrive at school about an hour before the start of registration or early morning meetings to get my personal work done. I tend to stay at school for about an hour extra on one day a week to do marking/planning. I imagine that I work about 50 hours in a typical week.