There is a mention of the potential long delays potentially affecting some players in the Dorset Open this Friday evening and weekend. But there have also been reports of delays getting to some league matches, including not arriving at all. Delays at peak times of over an hour seem unfortunately common
This is copied from the notes on the Congress, but obviously applies at any time, especially late afternoon and early evening:
POSSIBLE DELAYS ON THE A338 SOUTHBOUND If you are not familiar with this area, please note there will be likely traffic delays, especially on Friday evening, travelling south on the A338 after the Ringwood Ashley Heath roundabout and before the next junction, Blackwater. It is due to a 9 month project to improve the slip roads at Blackwater junction. 1 lane going south is coned off and so all traffic is diverted to the remaining lane, with consequent very long delays in busy periods. You may wish to check the situation in advance. Radio Solent runs regular traffic updates. Some local residents travelling from a Salisbury & Southampton direction have found it better to avoid that part of the A338 altogether and, e.g., divert more south to the A35 and via Christchurch.
The better news is the A338 going north of Blackwater Junction and to the Ringwood Ashley Heath roundabout is unaffected currently. But please do check if you were planning to come south on the A338.