I did it last year. It's a very small race and you can enter on the day - there were around 80 finishers last year. It's not hilly but has lots of very small ups and downs, like running over a lumpy field. It was muddy in places last year - some on tracks, some on grass and some on boardwalks. I would have done it again this year but my son is doing an athletics event that day.
I've just got a club place in the 2015 VLM. My half PB is 1:42 but that was in 2013. In March I ran 1:52 having been given a free charity place at the last minute. But the furthest I've run since then is 9 miles so I need to build up the mileage and stamina quickly. Current parkrun time is usually around 23:45 to 24 minutes, last 10k was 49.
Assuming I can run the whole thing, maybe the magical 4:22? Ideally I'd like to get under 4:15. But it's a first marathon and I haven't done an autumn half and don't have a decent mileage base.
Saturdays would be better because public transport is much better- it's a joke how early some events start - long before any or most trains go anywhere near the venue. But Sat is parkrun day and for that reason I prefer events on Sundays. I worked Saturdays for a while so did occasionally have to take AL for events, but that's the case for a friend of mine who works Sundays as well. Midweek evening events are great in the summer.