NOTAMS are the way to go because the BGA webpage link mentioned in the NOTAM does not lead directly to the competitions list!
I found it took me a while to find the list Mary Meagher refers to.
Seeing as the NOTAM expects pilots to go there, imho the BGA could have made efforts to make it more user friendly. A direct link to the list would have been useful, rather than trawling the site to find it!