Before hiring a metal detector you need to consider where you will be able to use it. In the UK, it is illegal to metal detect without the permission of the land owner. If you're not friends with your local farmer, here are some ideas of places you can detect without getting into trouble.
If you're lucky enough to live near a beach, it can be a great place to start metal detecting.
Think of all the things that may have dropped out of people's pockets or slipped off their fingers.
Most beaches are owned by the Crown Estate. You can detect on Crown beaches marked in purple on this map: https://thecrownestate.maps.arcgis.com/apps/Viewer/index.html?appid=0aac22685d2f4d78a2a3b0a5aa1660db
Many groups organise a weekly dig and you can join them for a fee of around £20 for the day.
Below is a list of a few groups:
A page to help people locate digs being held throughout the year across England, Wales and Scotland.
Digs in East Sussex.
Organise digs all over the Midlands: Nottinghamshire, Derbyshire, Leicestershire, Lincolnshire, Staffordshire and Yorkshire.
Organised digs across Herefordshire.
Digs across Hertfordshire and Essex.
Digs in Hertfordshire, Bedfordshire, Lincolnshire and Norfolk.
Digs in Berkshire, Buckinghamshire, Oxfordshire, Hampshire and Hertfordshire.