External rendering repairs or External wall insulation

I live in a circa 1920's house which has solid external walls (i.e. no cavity walls). The exterior has painted pebble-dashing and since the storms in Jan 2014 i have noticed water staining on the internal painted walls (possibly from water having seeped) in through cracks in the external rendering. I want to find out what kind of repairs I need to undertake to stop the rain water getting in or the best type of external wall insulation is that would be suitable for my home (given that my home can also get cold due to the solid external walls).