Go via aylesbury mate avoid the M25 altogether

its a fairly straight forward route tbh
I'd probably take the M3, you have to go a good way down the M4 (Reading) to get to Bracknell whereas it's only a few junctions on the M3. The time between the M4 and the M3 on the M25 is only about 10 minutes on a good day.
A few junctions down a normally empty M4 or a few junctions down a generally slow/standstill M25. I know which I'd rather choose.
The M25 is usually horrendous on a Sunday because commuters are going back to work as well as the Sunday drivers are out.