There's a slip at Padstow itself but it's narrow, steep and tidal from memory. Not used it myself. Car parking probably ok as you're out of season. One at Wadebridge too and it's good and wide, but no adjacent parking other than the road although there's a number of decent car parks in the town - only used this one for launching kayaks. Again, tidal.
Always wanted to give the Camel estuary a go as its a beautiful place.
Mind the Doom Bar