As advised by everyone here, I just went out and enjoyed it. Warming up beforehand was easy, plenty of space and time to stretch, walk, jog. Lovely volunteers everywhere and there was a briefing for all us newbies beforehand.
Official time was 34:42 tho I clocked it on Strava a few seconds under that. My only previous 5k was W9R3 a few days ago which was 37:50.
Absolutely loved the experience. Can't wait for my next one. Must remember my cool down next time tho...