Hi Dugcole and welcome to GoY. You don't say where you are in the UK could you edit your profile to tell us which county you are in. If you are in the south of England then you can plant out now but will need to water consistently due to the drought. If, like me, you are up in northern Scotland then you wouldn't be able to plant out at all need to go in a cool greenhouse.

We are in Sussex and have planted out both cougettes and marrows that are growing well.
I agree if you are further North then sheltered area or galoush is a good idea