Hi Mike
I too have been into Lyme Regis a few times, usually using a visitors buoy, or the walk-ashore pontoon. The harbour's usually pretty full! We have a member there - look in the handbook for P21 no 46.
If you're feeling adventurous, you could consider Axmouth - definitely one where local knowledge is necessary, so look in the handbook for P21 no 57.
I've also been into Teignmouth, which I liked, and was pretty straightforward.
One I haven't tried is the River Otter at Budleigh Salterton - see here!
One tip when heading NW from Portland using the inner passage - go west for at least a mile from the Bill before heading NW, otherwise you'll hit the southerly stream along Chesil Beach.