As said above – get to Eastborne – then SDW to Winchester.
From Winchester Head south east past Hursley to Romsey and then onto the New Forest. Basically you are aiming for Ringwood.
At Ringwood Jump onto the Castleman Trailway and follow it through to Poole. Then scoot down to Sandbanks, over the chain Ferry into the Purbecks.
In the Purbecks go onto the main ridge towards Corfe, go through there and up onto the next set of hills, through the ranges and past Lulworth Camp, out towards Rinstead Bay, then North west to White horse Hill and go past Weymouth.
The Onto White Horse Hill, Past the Hardy Monument, Down towards Abbotsbury and then a bit of road along the cliff top toward Bridport.
I’m Afraid after here my knowledge runs out but I’m sure someone else can continue…