We do need a photo. What colour is the roof?

You can borrow wallpaper books from suppliers and compare some you like by holding the samples up to your walls. Be sure to test how well they complement each other at different times of the day under different light conditions. I know it's hard to know for absolute certain how a particular wallpaper pattern will look on a large scale, but it's a place to start. And the people at the decorator stores will be happy to advise you.

Yeah. I agree with Hayley. Upload it into an ideabook and then i think you can use colour picker

I can't quite follow what you mean by 'we must keep the red roof' ? Are you not painting it , or repainting in the same colour , or would you consider a different shade ? Personally , with the White Duck , I'd go for a bolder red roof , with black or charoal gutterings , stay with the crisp white windows and veranda uprights , and the end detailing on the roof , but the window sills I'd do the same red shade as the roof , and the deck a mid grey . Oh , and also , although its cliche'd , I'd do a 1 metre tall white picket fence and double gates in the crisp white , get rid of the wire mesh haha , so everything about the house and fence looks crisp and themed , but also 'period' .