This looks like Steatoda nobilis, the so-called 'noble false widow', the spider which the media make such an unjustified fuss about. It has been frequent in the southern coastal counties of England for a great many years, and is nowadays frequent and abundant in many areas of southern England and Wales, including the south coast, south-west, south-east, London area and East Anglia, and increasingly much further north. The media frenzy caused by this spider is unwarranted. Steatoda nobilis spiders are unobtrusive, have no interest in attacking humans and would only bite if they were put into a position where they do so as a defensive reaction. Honey bees and social wasps pose a far greater risk. There are a number of other 'false widows' in Britain, some which are native or have been in the country for centuries, so there is a lot of misinformation about these spiders.
The uploaded photo On Conservatory door outside is a garden spider Araneus diadematus. These become adult in late summer and early autumn, and then their presence on their large orb webs is often more obvious in gardens. It is also a very variable spider in terms of colour and depth of markings. They are harmless to humans.