Only a few wateers have 'em in down there.
Grand Western Canal - shallow "cut" that runs from Tiverton up towards the Somerset border. Very weedy, even this time of year, lots of jacks in some bits of it but rarely does much over double figures.
Some of the remoter bits are little fished, esp round Sampford Peverell and above Halberton.
Good fun but little chance of a biggy.
Exeter Canal - A deep ship canal that runs from Starcross into the city centre. Deep and difficult but has a pedigree of big fish to low 30s. Best results I had were around the city centre or between Double Locks and the by-pass bridge. The very bottom end is little fished, I had a couple of big fish there years ago but I think it's had salt ingree problems since.
River Exe - they're in here too, though you rarely see anyone after 'em. The city centre bit, esp between footbridge and True's (?) Weir was pretty reliable, as was the pool further up by the Mill on the Exe.
Not sure the river's worth bothering with above Exeter.
Trenchford Reservoir - I haven't fished this but I've noticed it's started getting in the weeklies every now and then.
Slapton Lea was a legendary venue forty or foifty years back, I've fished it a few timesd and don't even think I ever caught anything on there. You could hire boats, I think from the hotel at Torcross.
e-mail me if you want more info - I've still got a load of old notebooks from back then somewhere at home.