It is quite a fast course. It is a little hilly outward, with a faster return. I usually run the second half quicker.
I haven't run the Marwell, so can't compare it. It isn't the fastest 10k course that I have run, and my best time for it is 37.12, set way back in 1991.
It is a friendly race, and goes round southampton common. They take entries on the day. I would recommend it to you.