Go onto your local council website and find the planning dept. You can apply for pre-planning consent which means in principle they will agree to the erection of a fence higher than standard. The more info you give on the application the better -for instance, the total height, the materials to be used and most importantly the location. Its highly unlikely you will get planning consent for a fence over 2 metres that borders a main road. Should they agree in principle then they will ask you to apply for full planning consent, this will be posted outside your property and anyone affected by the fence, neighbours for example, will be able to voice their opinions. Pre plannning consent costs around £40. Its a lot of bother for a fence to be honest.