Hand Solo
If you really know what you are talking about, then try not to make small but irritating mistakes, please:
You'll get 4 x 7 day blocks of leave (which you cannot work in)
You actually get 1-7day block and 1-8day block in each of summer and winter seasons, which may be taken as above, or as a single 15 day block.
NN may be including 'Wrap' days which are a couple of days taken either before or after each block of leave/DFW which you cannot be rostered to work on if you choose not to be.
Again you get 3 'Wrap' days before/after each block of leave and 1 non-assignable day before each DFW.
There are 2 DFW per year each giving 7-days free of work (*).
Leave and DFW days accrue proportionate amounts of credit, so a 15day leave block = 50% of the due work in a 30day month.
This makes in total (2x15 days + 2x7days) 44 days of credited days off, plus 6 days surrounding leave and 2 days before DFW which are uncredited, ie 8 total.
That to me totals 52 days, admittedly not the 56 of N_N, so I'm not quite sure where that comes from.
Whatever else
is wrong at BA the T&C's for leave are excellent.
(*) The DFW may be worked in at personal choice, the work can therefore be used to build up a credit surplus aka a bank, against which less work can be carried out in subsequent months.