In most countries, radio use is regulated by law, depending of frequency and use and if you have a radio license and/or certificate.
Sometimes the output must be limited to a certain power(Watt) and then you could regulate your radio.
For saving battery, when talking to another radio nearby, you could also lower your output.
Don't know about UK but I guess that you are not allowed to send with 2W overthere.
May you enjoy peace and good health !