I wouldn't worry about feeding it for about 4 weeks anyway. When it stops blooming, you can move it outside, either in a pot or plant it out. If you grow it in a pot outside, something like Miracle Gro General Purpose will be fine, but if in the ground, a top dressing of a rose food such as Toprose in late March/early April, and another in June, will be all it needs.

Thankyou very much, I will know where to come another time.