I've fished it about 5 times and I've had mirrors to from 15-18lbs. I'm not so sure if there are actually any 30's in there. Spoke to a few people and it sounds like the biggest is 28lb.
It gets quite busy at weekends and the swims are quite close to each other so you get quite limited. Best to go during the week, I went on Tuesday to Wednesday and me and a mate were the only ones on there!
I also found that the fish just sun themselves all day and only feed when it gets dark.