The PAGB awards are a good measure of how your photography is viewed by other recognised and competent photographers, however in my view it's something to aim at rather than a reason to be able to put a string of letters after your name. It would seem Sandy that from the initial advice day that you should be able to satisfy the judges with the prints that you took for scrutiny.
The PAGB awards differ from those of the RPS at the middle and top level in as much the ARPS and FRPS are more directly looking for a style rather than an overall ability as with the DAGPB and the MGPAB.
To be able to enter for the PAGB awards you need to be a member of a club affiliated to the PAGB, to be able to enter for the RPS awards you obviously need to be a member of the RPS, although you can enter a panel for the LRPS without joining.
Whether either tickles you fancy is a moot subject however, and raises many pros and cons.