hi, first time poster looking for some help. i'm decorating my daughters bedroom, we have stripped the wallpaper of the wall successfully. we have a mixture of exterior walls and plasterboard int and the all have very patchy and flaky coat of paint left behind. we were going to re- wallpaper but couldn't find what we wanted so decided to paint.what can anyone suggest? we have bought some polycell basecoat but haven't used it yet