Size 9.5 Extra wide fit women's sandals in the UK
British high street chain Next has over 400 of their own shoes & boots range in size 9 uk (43 eu) online, although they may be rare in store. They also have footwear in sizes 10-12 UK from other brands including Yours, LTS & various sports brands. Their website navigation is not great on desktop, so I've linked directly to the Next brand size 9s as a starting point. But if you click on view more/all under the size filter list on the left, you can choose other sizes.
Specialists in extra wide shoes, from 2E to 8E widths. Mainly comfort and traditional styles with over 100 size 9 uk options. Smaller range of size 9.5 & 10 uk styles, with a few trainers etc going up to size 12 uk / 46 eu. You can also order a catalogue or view it online to see the complete range. Their width finder tools only go up to women's size 8 uk unfortunately.
UK brand specialising in luxury comfortable wide fit shoes up to size 43 EU, all made in Spain, with half sizes available. Their 43 generally corresponds to 10 UK, but some styles would be closer to 9.5 UK. Similarly some 42s would be more like 8.5 UK rather than 9. This should be indicated on the relevant product pages. Most shoes are an extra wide EEE fit except trainers & Grace pumps which are EE width. Good range of modern occasion shoes, including bridal. Ballet flats, loafers and sandals also available. There are also boots and smart trainers, but these only go up to size 9 uk. Ships worldwide with free delivery and returns for UK and USA.