120 miles a day is getting up to 30k miles a year, so you want something cheap that will be reliable until you destroy it. There's a bloke lives in Essex and works in Wales that did okay with a Clio 1.5 diesel. You can just about get a basic brand new Dacia Sandero 1.5dCi that's the same underneath for £8k, but you'll have to buy and fit your own radio and you don't get a/c.