On big tides there is a lot of water moving in the estuary and the current is too strong for easy fishing at maximum flow, especially if the river is in spate. You will need to fish over low or high water slack times or when the flow abates. On very high tides it is possible to get cut off at this mark so consult tide tables before heading out there.
Bait is a problem in West Wales. Mackerel or frozen raw prawns can usually be bought from Tesco in Cardigan, there is a tackle shop in Cardigan (Castaway Tackle Shop in College Row 01239 621856 ) which sells frozen bait and very expensive farmed, boxed ragworm. As you go through the High Street on the one-way system you will notice a small square with what used to be Woolworths to the right, immediately turn left down the hill, this is College Row, there is a car park about 50 yards further on.