Most standard 95 unleaded will have a 5% ethanol blend (E5). Some of the Super (97 & 99) grades don’t currently contain ethanol. The article in the link below gives some good info. Uk government is currently musing over the introduction of E10. Its entirely legal to sell it now but the vast majority of stations don’t . Some sites are running some E10 trials and there are some retailers lobbying to make selling an E10 grade compulsory as part of RTFO (renewable transport fuels obligation), so expect to see this becoming more prolific at forecourts. http://armchairbiker.com/ethanol-in-petrol-what-classic-bikers-need-to-know/
Pretty much all diesel and gasoline will come out of the refinery or be imported in its plain Jane no additives state to the relevant European standard. It is in the storage distribution terminals (which includes refineries) that ethanol is likely to be blended and then each customer (retailer) will then puts whatever additives in it wants to meet their desired specification. Most retailers including supermarkets will put additives in to even base grades. Then some brands will put other additives in To make their premium grades. There are so few distribution points in the UK compared to 20 years ago that nearly all of them have the capacity to blend in ethanol on site.
Incidentally, E5 and E10 doesn't seem so popular in Europe nowadays. According to a forecourt I use in southern germany ( run by an englishman) Many retailers are putting supplies back to super 95 rather than Ethanol blend as the main demand is for proper petrol.
There has to be a market for fuel bladder tank liners to fit the old plastic tanks that are not ethanol resistant. They can't be more costly than bespoke tanks made from hand crafted alloy sheet.