If you have a pension, either private or work place, that money can be doing good or harm. Switch to a more ethical bank, and to an ethical pension provider, and an ethical investment fund.
Buy local, use refill shops, grow your own, reduce your intake of meat, dairy and fish.
Buy from companies with high ethical standards regarding the people who make the clothing (avoid sweat shops and child labour). Buy organic cotton or hemp. Avoid synthetic clothing that drops microfibres every time it’s washed.
Carry a refillable drinks bottle and a reusable coffee cup. Take UK holidays. Buy less stuff you don’t need.