I'd try and get windproof rather than waterproof, staying warm is more important than staying dry. I use a Tenn Outdoors Windblock, which is excellent for cycling, IMO, but others are available, obviously.
Waterproof stuff won't be needed as much as you expect, I haven't used mine in the past 6 months (although I don't commute by bike every day) but a windproof top could be used for the next 7 months.
Is the windblock fleece lined? or is it one of those daft pack down to the size of a grape jackets. Looks good for £30. I was caught of in epic rain a few days ago, and was perfectly comfortable in just a merino base layer and summer jersey, dont think that will be enough when the temperature drops though.