Just had a quick look on google map and if it were me i'd fish the smaller of the lakes, it looks shallower(although this might not be good with the current weather trend

) and with more features. You can see the weed growth and where the machines have made trenches whilst digging, these will be features the fish will cling to. The perch will love any cover for ambush(seems to be some trees on the bank, along with some deeper holes), and the rest of the fish may root around dying weedbeds for food etc. Keep quiet on the bank and dont walk right up to the edge straight away, you never know what could be in the shallows(if it's not too cold!).
As for flies try them all! Small(and larger) standard nymphs(hare's ears/PTN's), woolly buggers in olive and black, tadpoles,bloodworms etc and bagger fry patterns for the Perch if you haven't already got them. Dont forget flies in different weights too, or carry shot.........
Probably most important it to cover plenty of ground(and depth), there might be much of the lake devoid of fish due to them congregating in one deeper "comfy" area, or they could be more active and patrolling/grazing(as most of the species you mentioned do). If you contact a fish stick around and try a few different things, i doubt it'll be easy but there's no such thing as a wasted day when you're fishing!
Good luck and let us know how you get on.......
Cheers,
Graham