how much do you want to spend?
what are the floors made of?
if you take off the skirting, and the plaster behind them, you can space the skirting off the wall with 18mm horizontal battens, leaving room to run the pipes between them. The top batten should be aligned with the top of the skirting to make a neat joint that can be painted, and the plaster repaired to run down to it
this is not a complex or difficult job.
in an old house the plaster may be more than 18mm thick and there might already be wooden grounds in the brickwork that you can remove
the plaster is likely to be damaged and some of it will fall off.
the main problem is some dummy putting a drill or nail through the skirting afterwards and puncturing a pipe.
