Bracken is a fern...
Clay is good... holds moisture & fertility.
I always hate to hear about how much work someone is putting into their garden... When the intended crop is turf...
I think the soil is fine... Although... standing water will always be a problem... Find a source of fill... make sure that you don't have puddles.
I think that you are always going to have spotty performance... turf needs sunlight...
Liriope is common... even in Scotland.
If you can encourage the clover... that would be to the good.
