Pick up the place-name info of here and other sites and go to: http://www.multimap.com/
You can zoom in to find street names and even get aerial pics of the place. It also gives routes. Great for passing the time when you can do a virtual walk of the coastline.
Theres a book Clive Gammon wrote in which he put maps of all the coast of Wales and marked where to fish on them. Sounds just the sort of thing your looking for. Its probably been out of print for years now but you may be able to get one by searching old bookshops or ebay etc.
If you are looking for maps of marks more local to you pop into Garry Evans in Cardiff and pick up one of his tide timetable booklets at about £2-50. In the back are a bunch of reduced OS maps which show all the local(ish) marks from the Newport coastline across to just past the Port Talbot coastline. It doesn't tell you much about the marks but if you need to know anything just ask on this forum. Garry and Colin in the shop have fished the coast around here and would be probably be able to tell you what you need to know.