There are a number of Steatoda species found in Britain, all so-called 'false widow' spiders. Three are possible in or near buildings, Steatoda bipunctata (very widespread), S. grossa (widespread and sometimes very frequent in the southwest, but becomes much scarcer further north and east, but in the last few years seems to be increasing) and S. nobilis, the one which gets the press for biting humans (originally confined to the south coast, now increasingly turning up elsewhere in southern England). Steatoda nobilis has on occasions been responsible for bites, and Steatoda grossa is also known to be able to pierce human skin, even though many of the cases publicized for this are almost certainly due to another cause, and there are other spiders capable of piercing human skin. Steatoda nobilis is widespread and numerous along much of the south coast, has been established in the Southend area of Essex since at least 1990, and in more recent years had spread widely and come much more numerous in England as far north as Norfolk and also south Wales.
The current media hype about 'false widows' (by which Steatoda nobilis is presumably meant) is beyond reason and irresponsible. See Evan's comments on this forum on 8th October. Also lots of misidentifications are being made because of all the hype. You can see the current distribution and information on the spider at summary
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