The River Test and the River Itchen are very easily reached by the UK's main trunk roads, being approximately 1.5 hours from London. The M3 and the A3057 run almost parallel to the River Itchen and the River Test, respectively. Most of the beats are less than 20 minutes by car from either.
By air and rail
If travelling by air the nearest airport is Southampton, 20 minutes away, with Heathrow and Gatwick both also within 1.5 hours drive. These airports provide ample opportunities for car hire for the onward journey.
If travelling by train head for the main line stations of Winchester and Southampton changing as required at intermediate stops between the two.