My 2c worth.
I'm based at Popham and tend to avoid CAS when going to either Duxford or CA.
From Duxford I'd go Woburn, Oxford (aim for Cowley which is on the eastern edge and easy to spot) Newbury, Chilbolton (Radio telescope, easy to spot) Alderbury VRP, Compton Abbas
That's a low level VFR route with nothing complicated about it and good ground features.
At a weekend you're unlikely to get an answer from Boscombe so it will be blind calls inside the CMATZ to let their flying club know what you're up to.
If the weather's good you can then start trying to cut some of the corners to shorten the route.
Try to be approaching CA from the Northern side. There is a large dark wood running along the south side of the a/d and a strobe beacon which shows up well against it.