If you try sandmere be very, very careful. There are loads and loads of silly rules and the baliff is pretty officious...
Get yourself booked onto the Isle lake for a day. I fished it about 4 weeks ago between 10.am and 2.00pm and had around 25-30 fish averaging around 12-14lbs. Great fun on barbel gear.
upper Thorney croft is not a bad water also.
Good luck