Maybe Papaver paeoniflorum 'Pink Paeony' ?

Certainly one of the hardy annual type of poppies. of which there are a large number of named types. Papaver somniferum Paeony flowered is the usual one.

it is such an easy plant that self sows and you get many different forms popping up. As ar as i am aware there are 'series' ie pink shades.

It's just a double flowered papaver somniferum or as Owdboggy says, the paeony flowered one. Once you have it, you will never get rid of it as it seeds everywhere. But no bad thing as it's easy to pull out where you don't want it, and you can leave them where they suit, though the flowers don't last long.

They are beautiful poppies that seed freely and I love anything that seeds freely in my garden!

Yes, this is what bobbed up in my garden in England and kept on appearing year after year.

I am struggling to grow poppies in the CR though which is very annoying since just now the fields here are ablaze with red poppies, blue cornflowers, and white marguerites - the colours of the Czech national flag :-)

These are gorgeous, but how did you get it to grow on it's side like that!!!!