Although you havent stated where you are travelling from or at what time, using the same power of foresight that I used to be able to tell you what they traffic will be like in 3 days time I have been able to find out. I am therefore able to give you the following information.
Theres going to be an accident involving two cars on the M23 (no one seriously hurt) that will close one carriageway for over an hour. The M25 will be busy but moving, you will be able to acheive and maintain a staedy speed of 50 miles an hour. There will be a broken down lorry on the M6 and the outside possibility of blustery wind and rain for a period of 37 minutes whilst you are on that road.
On the way back you may be hindered by someone hogging the middle lane of the M6 when you are trying to overtake. It will also be dark. Stopping to have a slash/use the toilet/get a drink/stretch your legs will delay your journey so you may want to consider if its worth it.
It will take you two hours to get there and two and a half bhours to get back.