The supply here is 245-250V+, as most products are designed now for the "harmonised" voltage standard, bulbs and heater elements (such as ovens, showers and kettles) don't last as long as they should. Also some capacitors in SMPSU's are right on their limit for a 230V rated supply and do not cope very well with the UK voltage.
I remember when products (usually with linear transformers) had a 220/230 and 240V setting.
My lutron system will fade incandescent/halogen bulbs down so low they are barely visible, it is a fantastic system but it does not play nicely with some LED's and none will dim as low as traditional bulbs.
Do some LED bulbs run at reduced brightness? Many modern LED lamps contain a high voltage string of LEDs and a linear regulator, which drops the last 20V or so. It works fine, when the mains voltage is within the normal specification and the lamp is cool enough, but if the voltage is too high, the linear regulator can overheat, causing it to throttle back the current limit.
Have you spoken to whoever runs your local electricity grid?
If they won't reduce the voltage, you could reduce the voltage to your house by adding an autotransformer. A 1kVA 230V:25V mains transformer, wired as an autotransformer (check the phasing of course) could be used to knock off just over 20V off the supply voltage and should give enough current capacity to power a ring of sockets and a lighting circuit. I don't know if such an arrangement would conform to the wiring regulations. Ask an electrician, if you're unsure.