Perhaps a day is not enough and you would like to spend a whole week concentrating on your painting skills. I can offer a couple of possibilities:
In 2020 I am working with Arte Umbria to tutor a painting holiday in rural Umbria for the fourth year. In 2019 it was a sell out! The setting is stunning, the food is delicious and the pool is cool. Its 3-10 July 2020 and you will need to go to their website for full details:

If something more exotic is what you are after and it is a holiday-of-a-lifetime, then why not join me on a photography and painting course in India? Next autumn we are headed to the Corbett Wildlife Reserve in Uttarakhand to the jungle where we will get the chance to see tigers, leopards, jackals, sloth bears and elephants, a wealth of spectacular birds and, along the rivers and lakeshores, crocodile and other reptile species. Finally there is the option to head into the mountains to see the breathtaking Himalayas, painting, photographing and trekking. You can find full details on the site.