Do very little in the final few days, if anything. Maybe 8 to 10 miles is the max this weekend, but if your knees and joints are sore, complete rest could be even better. You need to make it to the start line. It's better to be 5% under trained than 5% over trained, because that is defined as being injured.
Concentrate on your food. You're not burning the calories so match the intake to your need (you may still be a little hungry, be careful). Thirsday, Friday, move diet towards carbs with less fat and less protein. Think about Saturday's breakfast and toilet strategy. What fuel for the race?
Get your gear ready, prepare your support team, and as them for a little bit of Mum time.
Avoid time on feet on Friday.
On race day, the first 6 miles should feel like you've got the brakes on, mentally hold back the pace. The next 7 should be pleasant. The next 7 need a bit of focus. The final 6 need a lot of focus, but you've done the miles, have faith. It'll hurt, but pain is temporary, success is forever.
When you finish, say "never again" then plan your next one with the other forumites.