2013 Peugeot 208 oil leak, head gasket

If leak is from head gasket and is still leaking from same place and work carried out correctly , either head or block are warped .

" Not very much but just enough to cover everything by oil under the engine and specially the gearbox. " That's bad .

Could check crankcase breather is not blocked and causing excessive pressure to build up resulting in oil leaks

Crankcase breather is ok, checked. I have replaced the gasket twice now. The first time the tightening was not completely successful because of a bad tool, I thought that was the problem. The cover was in the machine shop and it was checked that it is straight. The engine side was checked with a steel ruler. The second time I also used the product VHT Copper Gasket Cement, now the tightening was successful with a better tool. The leak is now smaller but still dirty. Would it be possible to use a thicker sealant, e.g. Loctite products?

" because of a bad tool, " " successful with a better tool." I dont know what tool you are blaming , possibly a torque wrench . Or what cover you are referring to " The cover was in the machine shop " maybe the cylinder head which should have been skimmed and pressure tested . Using VHT Copper Gasket Cement or similar should not be needed as it is admitting there is a fault between head . block and gasket and trying to compensate rather than find / fix fault . Hope you get it fixed

Sorry my bad english... I'm a Finnish. And sorry to waste Your time.
Anyway, I appreciate your reply.
Bad tool = torque wrench torx E12 which should be long model because of the cylinder head construction in the middle of the cylinder head. It was diffucult to get the right tool.
The cylinder head has been skimmed before the first installation and skimmed slightly again before the second one for to be sure it's really ok.
You are right, Gasket Cement or similar should not be needed but please tell me how to check the surface of engine block ? There are no scratch or anything to be seen and the surface is clean and bright.
The reason for changing cylinder head gasket was due to camshaft belt, the tension roller failed and the belt jumped from the camshaft, some valves were hit by pistons. Before the failure there was no leak at all.

Why not to "compensate" small failure by using some additional sealant liquid, it´s very common way to fix small leaks and basically to be sure that the sealant doesn´t have any leaks ?