The tavy and it s tributaries is very close although there is a long waiting list for full membership but the open waters are very good.
Catchbook - Social Fishing Network - River Tavy, Walkham and Plym, Devon
The Devon avon is a very good little river with solid runs of sea trout and back end salmon till end of november.
Catchbook - Social Fishing Network - River Avon, Devon
The plym and the meavy can be ok during the summer and autumn but not as good as the tavy or the avon.
The erme and the yealm are also near by and have modest but worthwhile sea trout runs.
The mouth of the yealm can be very good for sea bass as well.
The dart is a little further away but access can be difficult or expensive.
Hope it helps a bit.
Ed