Ultralight backpacking is as it sounds. Get a small, lightweight material backpack, fill it with only the barest of essentials, eliminate all else no matter how hard that is to do, and go. There are two main ways to go super light. You can buy the lightest equipment, clothing, accessories and travel gear there is, which tends also to be the most expensive. Or you can go bare bones and take less than you need, purchasing supplies on the way.
Lay out the things that you need most, and leave half of them behind. If you are planning on staying in hostels on the way, you can wash your clothes out daily if necessary as long as you have a second set to change into. Two will do. If you are camping your way across the UK, you will need rain gear for certain, as well as a tent, sleeping bags and the like. This will increase your load significantly, although ultralight camping equipment is available at a cost.
Traveling with one companion or more can be a great help as the heaviest of items, such as a tent, can be either broken down amongst you all, or passed around day to day. In hostels, having companions can often allow you to book a private room for two or three, whereas singles most likely will sleep in a large dorm. When it comes to rail ticket, groups of two or more are eligible for saver rates as well.
