...if you are flying in competition, WHICH HAS BEEN NOTAMMED,...
Mary, the NOTAMs are not very helpful.
E.g.: MAJOR GLIDING COMPETITION INCLUDING CROSS-COUNTRY ROUTES. INTENSE ACT WI 10NM RADIUS xxxxxxN yyyyyyyW (aerodrome name). UP TO 100 GLIDERS AND 10 TUG ACFT MAY PARTICIPATE. GLIDERS WILL NORMALLY OPR BLW THE INVERSION LVL OR BTN THE TOPS OF ANY CU CLOUDS AND 500FT. It then provides contact details for more information on daily task routes.
Bearing in mind that tasks may be several hundred km long, that tasks will not be published until mid-morning after the competition pilots' briefing (and may be changed on the grid only 20 mins before launching starts) when power pilots will have completed their flight planning, that there may be multiple contests on at the same time in the same part of the UK then the only value is to warn you that there could be more than the usual numbers of gliders anywhere within 100-200 miles of the launch site - but outside controlled airspace.