Peugeot and Citroen cars (PSA) I found were the cheapest to purchase + insure. I think it's because they have some of the cheapest parts, and they tend to depreciate very heavily. Also they tend to be pretty reliable and rust-free. The old TU engines (they have been phased out now, but can be found in 207, C3 II and earlier back to the 80's) were very reliable engines known for going on forever and needing minimal work. The newer engines I would avoid, at least in higher mileage cars.
Vauxhall Corsas, despite me never being able to get on with them, also have a good reputation. They are inexpensive and reliable, although I always found them unexciting and a bit unpleasant.
Also don't count out higher displacement cars, often the insurance between a 1.0 and 1.4 isn't that different (occasionally higher displacement will be cheaper). And if you find a great deal on say a 1.6L, even if insurance is more expensive the overall cost may come out to not be significantly more expensive than a regular priced 1.2L. You'll definitely thank yourself with the extra few horsepower!