A Sussex Grand Prix race so should attract a strong field. Pretty much dead flat and the main issue will be the wind and how strong it’s blowing. It’s an out and back course where you complete 2 loops. So not ideal in that sense.
It’s a 9am start so get yourself there in plenty of time to warm up. You should be starting your warm up around 8.20 to give yourself 10-15 easy jog, following by dynamic stretches and running drills. Then also a last toilet stop if needed.
If it windy then try and find someone to tuck in behind and protect you from the elements. Then save some energy for when you turn back around and have the wind behind.