One of the best actions you can take is to buy peat-free potting compost. You can also make your own compost from garden waste. This can be used as a soil improver or mulch for fruit bushes and shrubs. A simple container can be made from four posts and some chicken wire into which you can tip all your fallen leaves in the Autumn. These will rot down slowly to make leaf mould, which again can be used as a soil improver or mulch. Peat bogs capture carbon and keep it locked up for years. The extraction of peat means that this carbon is released back into the atmosphere. Once depleted, a peat bog takes many years to recover.
Instead of using plastic pots to sow vegetables such as broad, climbing French and runner beans, you could save up your toilet roll innards and use these. Just place the rolls upright in a seed tray or plastic supermarket vegetable tray, fill them with compost and sow your seeds. Just pop the young plants, still in their cardboard pots, into the ground when they are ready for planting. The cardboard will rot down in the soil, allowing the roots to spread.
If you do use plastic pots, these can be reused year after year, providing you give them a quick wash each time you re-use them. If you have lots of plastic pots, some charities and garden centres will accept them for re-use. If your local garden centre does not do this, then suggest that they do so,