A tent is only one part of a good shelter setup. The small accessories around it often decide how comfortable the night feels, especially in the UK. Rain, mud, wind and condensation have a way of exposing weak points quickly.
The first upgrade I would look at is tent pegs. Many tents come with pegs that are fine for campsites but not ideal for soft moorland or exposed pitches. A few strong Y-beam pegs and a couple of longer pegs can make a tent feel much more secure.
A footprint is worth considering if your tent has a thin floor. It protects against abrasion and keeps the bottom of the tent cleaner. That is especially useful when packing up on wet grass. Just make sure the footprint is smaller than the tent floor, not larger.
Extra guylines are another underrated accessory. If your tent has additional guy points, use them when the forecast looks unsettled. They reduce flapping, support the flysheet and help the tent keep its shape in wind.
A small repair kit should live in your pack. It does not need to be complicated. Repair tape, a fabric patch, spare cord, cable ties and a pole sleeve if your tent uses poles will cover many common problems. You may never use it, but when you need it, you really need it.
Dry bags also make tent life easier. Keep your sleeping clothes, electronics and spare layers in dry bags. Condensation, wet packs and accidental drips are common enough in UK camping that it is worth protecting the important stuff.
A small cloth is surprisingly useful. You can wipe condensation, clean mud from the groundsheet or dry an area before applying repair tape. Choose something compact and quick-drying.
If you camp in Scotland, insect protection matters. A head net and a tent with fine mesh can make summer evenings much more bearable. It is not glamorous gear, but it can save your sanity.
For longer trips, I also like carrying spare cord. It can replace a broken guyline, extend a pitch point or help with an awkward anchor. A few metres weighs very little.
The best tent accessories are not about carrying more gear for the sake of it. They solve real problems: wet ground, loose pitches, broken parts, condensation and poor organisation. Start with better pegs, a repair kit and dry storage. Add the rest based on where and how you camp.