I grow them indoors in a very bright sunny window. They have to be right next to the window. They have been blooming all winter. My room is kept at about 70F. I'm not sure you have the light for that in winter. Your weather is overcast a lot, right? You can carefully give them some half strength fertilizer. Don't overdo it. Keep watch for spider mites. I have had them appear in my grow tent where I have mostly bromeliads. Like Tarev said, it's a good experiment, and I wish you good luck with it. Growing them in London would be amazing and so satisfying.
