The high hedge legislation has 3 requirements.
1) it must be a hedge - if it's a single tree you're out of luck
2) it must be over 2 m high
3) if it satisfies these you can apply to the council and they will make a judgement as to whether it meets the third criteria whether it affects your "reasonable enjoyment of your property"
Council policy on this varies from council to council - I think there are only 3 that make no charge for this, some refund the fee if they find in your favour.
Check with your particular council, they'll probably have details on their website or give them a ring.