OK, I just spoke to Maree at Marine Rescue Swansea. She was very helpful and gave me a bit more information about the depths and tides.
She said the current information was "1.6 metres, plus the tide" at the bar. The only other caveat is the swell and wind direction. Obviously going in on the incoming and out on the outgoing was preferable, but not imperative.
She mentioned booking the bridge, taking care on the drop off at very low tides and making sure you round moon island well to the east to get a good line on the leads.
She also said, if you encounter a problem, call them and they'll come tow you out of trouble.
She was really, really helpful and said she hoped we enjoyed our sailaway
Michael