Your budget means you could comfortably purchase a secondhand Baikal IZH46 which is a good target pistol and keep the rest to fund a PCP in the future. Alternatively save a bit more for a PCP, as you might be lucky to get a secondhand PCP (e.g. Walther LP200/300, Steyr LP2) from approximately £550, however you need to take account of being able to fill it so will either require your own cylinder or easy access to one.
As with all pistols try the different options before you buy as different manufacturers suit some people better.