You can get daylight bulbs in decent art shops. They throw a very blue-looking light to the untrained eye, but daylight *is* blue. (Most daylight bulbs are carefully controlled to replicate the colour temperature of daylight)
So - near here, the art shops to pursue (via www.yell.com for address, tel. number etc) include:
I have not yet come across any art shops in SE1, by the way.
I forgot, it might be worth calling Silverprint. They are a very helpful and friendly photographic supplier in SE1, on Valentine Place, just off Webber St. Find them on www.yell.com for their number/address.
That's the kind of thing they might have as well (photographers need daylight bulbs to gauge colour prints, contact sheets etc.)
whilst in derby there was a craft shop - needles...sewing silk etc. if you cant get them when I am up next I could get some for you if you have difficulty...they have differents watts....apparently its better if you sew by daylight?