I have just been into my local Homebase at Bedford and they have a lot of Philips 11watt eenrgy saver bulbs for 49p (usual price about £2). I have bought these before at this price and they come up to full brightness straight away and are about the same size as a normal 60watt bulb.
Philips 11 watt Energy Saver bulb
11watt (equivalent to 60 watt tungsten)
10 year expected life
I don't know whether this is Nationwide and does not seem to be on the website