So had minor op today, and now the scar is very very itchy

[Saltire]

Well it's not a scar is it, it's a wound, with stitches. And the local anaesthetic is weraing off, and it feels very itchy and tingly and sore.
Any suggestions to stop me clawing at it

Cool pack? Like one of those gel packs for the children?

It's on my head though, would need to tie it on with a bandage

Take painkillers to take the edge off it. Will you be allowed to shower your head anytime soon, or does it have a dressing/have to be kept dry?

It has a waterproof dressing on it, but I have greasy hair and it needs to be donw every day, so might try tomorrow with DH's help

Maybe a bag of frozen peas wrapped in a tea towel on your head? (in the privacy of your own home obv.)

Frozen peas sound a good idea. Otherwise I urge you to leave it alone to avoid infection. I had an infection in a wound in January and it was horrid, so leave alone if you possibly can!