What's your subject matter? I used an inexpensive Manfrotto 3047 pan/tilt head with hexagonal quick release plates for years with good results, shooting mostly landscapes. The current 3039 is basically identical, going for $189 (U.S.). I think this falls within your limit, if I have my dollars/pounds sterling right. It wouldn't be so good for wildlife, but it's rock-solid and supports anything up to 20 lbs.
Ballheads are surely more convenient, but you definitely get what you pay for in this area. For about $300 (somewhere around £200) you can get a good ball head with standard Arca-Swiss style quick release from Kirk Photo. Manfrotto has many ballheads, but for reasons I cannot fathom they all come with proprietary, oddly shaped quick release plates that don't standardize with anything.