I believe current thinking (based on DNA) suggests that after the ice age, the "Celtic fringe" - Cornwall, Wales, Scotland and islands, Ireland - was settled by people who came up from the Basque country, which would probably be the northern Spain bit.
Central Britain (basically England) was settled by people who came overland from somewhere round Bulgaria/Ukraine - quite a wide area but it might be the "central Europe" you mention.
I don't know whether an individual test, at least for females, would tell you much more than that. I could be wrong, so it's probably worth googling it and reading as widely as you can, since they're not cheap.