Racks and panniers
If you want to carry a heavier amount, it’s worth investing in a front or rear rack on which you can carry bags or panniers. Rear racks will usually fix to the seat stays and the rear dropouts. Some bikes won’t have eyelets to fit a rack, so it’s worth checking when you buy if you think you are likely to want to use racks, although it is possible to buy adapters and mounts. Rear racks will take more weight, but beware of going up steep hills as your bike may tip if it’s heavily loaded at the back.
Once you’ve got your rack fitted, you can invest in a couple of panniers (you may prefer to use just one, but bear in mind that the imbalance can make cycling a little harder) or a bicycle bag or satchel. Bicycle satchels will clip onto one side of your rack and are much more practical than panniers if you need to carry things around on your person during the day, and they’re usually a perfect size for A4 folders, so they’re a popular choice amongst students. Bicycle bags may clip onto the side of your rack or fix onto the top.
Bags and satchels can range from £15 - £80; panniers usually start from around £20 each. Several pannier manufacturers also make panniers designed to safely hold a laptop.