I had initially planned to route around the CTA and go up to 'Chedburgh' but thought as it is disused it won't be a good VRP
This is the route I would select. It is easy, unstressful and Chedburgh is actually rather obvious.
chedburgh from the air might be difficult as I couldn't locate on google earth
Excellent initiative as there are
DISUSED AIRFIELDS and there are
disused airfields.
Look up 'Chedburgh' on Google Maps - the outline of an airfield is obvious just south of the village.
You are perfectly entitled to fly as close to CAS as you wish, but you are not entitled to enter it without permission. You seem to be planning to fly less than 1/2 mile from the boundary which gives you no margin for any errors - No lapse in concentration; accurate, correct Heading Holding, DI perfectly aligned with compass and, as you have already identified yourself "could end up blown into the edge of the CTA".
There are quite a few Infringement Reports where the pilot says, after the event, that they should not have planned to fly so close to the edge of CAS as it gave them no leeway and that this was contributory to their infringing.
There would be no problem flying this close to airspace if there were obvious landmarks (eg a dual carriageway) that could always be kept between you and the airspace boundary - but any landmarks seem pretty sparse in this part of the SE and you cannot move your Track slightly further out due to Ridgwell Gliding Site.
You don't have a GPS. Do you have a DME? If so set it to Stansted and, if you really want to fly this route, never let it show less than 11 dme distance.