Rocker Box cover gasket AKA Cam Shaft Cover gasket

As there are signs of oil around the spark plugs I decided to order a gasket with intention of replacing it later this year. Bought one described as “original” rather than “after-market”. This is known as camshaft cover gasket and has part number 
Not sure exactly what I was expecting but definitely not a preformed plastic sheet type of thing.
Has anyone fitted one of these, and if so was a sealant of some form used?

I had thought it might be a traditional fibre gasket or a rubber gasket but definitely not a pre-moulded hard plastic sheet.
Any comments please?
 

What car is it for? MGF/TFs use this type of rocker/cam shaft cover gasket.
Glyn.

It is for a 2003 MGTF135

So as I said MGF/TFs use this type of gasket.

So if this is the correct gasket my question remains. Is it stuck down with sealant as I struggle to see how a hard plastic sheet with a few ribs in it over a large area can ever form a reliable seal.
So if anyone can shed light on this I would appreciate it.

Use it if you feel it'll do a good seal. Can't do any harm but its down to you.
Good luck. Glyn.