Lorne
(warning - long post. I hope it will be useful to others)
If you are strictly limiting your list to British birds, I understand that there are several British option, of which I have no experience.
If you are interested in International birding, there are several available packages for both Mac and Windows.
For Windows there is
Avisys,
Birder's Diary,
Bird Journal,
Wings, and
Swift.
For Mac there is
Wings and
Bird Brain. All of the Windows packages will run well on a Mac using either Bootcamp or Parallels. None of them work with Crossover unfortunately.
Then there are the online listing options, of which I am only familiar with
eBird. Recently eBird expanded its scope from the Americas only to World wide. I enter all my sightings on eBird to make them available for ornithological studies, but I don't use it as my primary listing software. It is OK for simple reports, but it doesn't have the options that any of the software packages do. Still, it would be viable if you want simple listing. I would recommend using a local software product and uploading your sightings from it to eBird. All of the packages have a facility to let you do that. eBird uses all American species names.
I was going to do a mini-review of all the packages, but in the interests of keeping this post a tolerable length I have decided to upload that as a pdf attachment.
As for Bird Journal, I think you might look at it again. The programme has a lot more depth than appears at first glance. There are synonym files available on the website for British names. The graphs are useful after you have a decent amount of sightings entered, but they can be ignored if you're not interested. Ordering by taxonomy is almost ready, and will arrive as a point update. I agree that the lack of this facility is the software's weakest point.
I will upload the attachment later today.
Good birding
Alan