24/12 was great last year and the best course for that type of race I’ve ever been on, in fact Newnham and the SSWC2006 course at Aviemore are my 2 best courses. Great singletrack and not massively busy like MM so you can actually enjoy the trail at your pace for most of it.
As for the relay, you can swap the baton after how ever many laps you like, so you could do 2 or 3 then hand over if you fancied it. 1 lap at a time is prolly the most common though.