Work Stay in the UK

Hey everyone! Looking at doing my first working holiday away and hoping to book it within the next 3-6 months (just gotta save for how much I need) and wanting to be able to stay in the UK for 6-12 months. I currently live in brisbane, Australia and I’m 19 and have worked in a customer service/retail position for over 4 years. As well as structural landscaping and tree lopping as a labourer. Wanting to be able to live in the UK, preferably either London, Manchester or Edinburgh, or backpack all throughout. I don’t know if that’s fully possible though. Not necessarily sure if this is enough information to answer but any possibility anyone has any advice on what company or website to book through? Or any direction to take this? Any helps appreciated :)