Firstly, sorry its my first post on here and im asking for help 
I bought a td5 disco 2 a few days ago slightly cheap as we established the turbo needed replacing, so we factored that into the price.
We assumed this because there was an oil leak and it was all fresh oil around the turbo area, and it had a little white smoke on startup, common symptoms for needing a new turbo.
We were driving down the road today, about 35mph, and the engine revs shot up through the roof and the engine started nocking and a **** tonne of smoke out the back.
We switched it off almost immediatley and pulled over, tried to start it and it was fine, drove me the half mile route home.
Checked under the bay and theres still a fair bit of oil under the turbo and the oil level is sky high! Most the way up the dipstick..
Took it round the block again to see if it had stopped fully, and it happened again so just rolled down the hill to my gates.
The engine oil level remains at about 6inches high on the dipstick and is very watery.
After abit of research myself iv found the heads are prone to cracking and i can only assume diesel has forced its way past the rings.
Is there anything else it can be? Other than an injector sticking wide open?
Is it a case of a new headnand an oil flush? Or is it going to need an engine replacement?
If so is there any guides kicking around which will make my life easier when doing it?
Sorry about the 21 questions guys, as you can imagine im stressing a little now

I bought a td5 disco 2 a few days ago slightly cheap as we established the turbo needed replacing, so we factored that into the price.
We assumed this because there was an oil leak and it was all fresh oil around the turbo area, and it had a little white smoke on startup, common symptoms for needing a new turbo.
We were driving down the road today, about 35mph, and the engine revs shot up through the roof and the engine started nocking and a **** tonne of smoke out the back.
We switched it off almost immediatley and pulled over, tried to start it and it was fine, drove me the half mile route home.
Checked under the bay and theres still a fair bit of oil under the turbo and the oil level is sky high! Most the way up the dipstick..
Took it round the block again to see if it had stopped fully, and it happened again so just rolled down the hill to my gates.
The engine oil level remains at about 6inches high on the dipstick and is very watery.
After abit of research myself iv found the heads are prone to cracking and i can only assume diesel has forced its way past the rings.
Is there anything else it can be? Other than an injector sticking wide open?
Is it a case of a new headnand an oil flush? Or is it going to need an engine replacement?
If so is there any guides kicking around which will make my life easier when doing it?
Sorry about the 21 questions guys, as you can imagine im stressing a little now