Debbie,
Hi. Three of the sites which you mention are local to me, as I live almost within sight of Bass Rock.
The Isle of May is a great place. There are two difficulties in visiting it. The first is that the road over from Edinburgh to Ansthruther (where you get the boat) is very slow. Alow two hours driving from leaving the motorway. The other is that the landings are weather dependant. There are often days when it is just not possible to land. Could be a problem on a tight schedule like you will be following. Not sure if I would keep the May on my list if I were trying to cram lots in to a very short time.
One place worth a stop as you work southwards is Dunbar. There is a ruined medieaval castle beside the harbour there with a colony of Kittiwakes. About 50 yards from the nearest car parking! Shoudl be possible to get level with a few of the lower nests from a small grassy mound. Mornings through to early afternoon will have the best light.
Another "drive in" seabird colony as you travel south is Saint Abbs Head in south-east Scotland. You can drive all the way out to a small parking area beside the lighthouse there. There are good seabird cliffs just north of the lighthouse. Some years are better for close nests than others on the cliff tops. However, it is a great place for taking group shots on the cliffs and on some of the sea stacks offshore.
The Farne Isles are a wonderful place. You should try to book a full day trip in advance. This lands on one island in the morning and another in the afternoon. You get longer ashore than if you take two separate half day trips out of Seahouses. The biggest and best boat operator is
http://www.farne-islands.com/index.htm. Agsin, landing is weather dependant. I have been unable to land on the Farnes in mid June in the past. If I were you I might think of trying for two days on the Farnes back to back and forgetting about the May. This will greatly increase your chances of actually managing a landing. Also, if you do get two trips, once you have been there you can think overnight about how to optimise your limited time ashore on day two.
Bring a hat! You will have to cross a tern colony as you land on Inner Farne. Mother terns can be picky about letting you along "their" path. There are usually a few chicks around the buildings at the top of the path. Worth bringing a close focussing lens for these e.g. 180 mm macro.
As for other lenses, 400 mm for flight. As for getting really good closeups of birds on the ground, I always advocate taking the largest lens with which you are comfortable travelling. When I go, I take my 600 mm and my extenders. A lot of photographers who visit the Farnes say that there is no need to take such a large lens. However, if you are comfortable flying with a 500 or a 600, you will get the benefit of your efforts. You sometimes get close puffins from the paths with a short lens. You can always get them a little way off of the paths with a long lens.
Do not forget the harbour at Seahouses at both ends of the trip. There are often good opportunities for close photos of Eider there. Also, there should be some confiding starlings, including youngsters.
Bempton will give you good Gannet photography. The cliff have sun on them in the mornings. Sometimes it is easier to photograph there without the sun (cloudy but bright), as a lot of the path has you looking into the sun. Not to mention the usual problem of brilliant white birds with some black bits making for difficult subjects in sunshine.
It is a shame that Bass Rock has become such an unfriendly place. Under the old ownership with a long established boatman fron North Berwick it was a wonderful place. Although this was also weather dependant, Fred Marr was superb at getting you on and off in rough seas. I was once on a non landing trip with him many years ago when we called in to deliver the Sunday newspapers to the lighhousekeepers despite the Force 7 winds. He could also put you onto Craigleith, a couple of miles west of the Bass. A small low lying island of Puffins. Alas, that is a thing of the past. Change of owner for the Bass forced a change of boatman. Also, Craigleith has become rather overgrown and that has spoilled it as a place to visit for photographers. Trips to the Bass are a real rip-off now. I, like a great many other photographers, refure to go because of the level of the landing fees.
I shall be happy to try to advise further if you wish. Feel free to send PM or e-mail.
Best wishes,
Peter