Halloween is nearly here, and Guardian Travel is once again asking its readers to share their creepiest holiday discoveries. This week's readers' tips callout is hunting for the UK's best spooky spots — haunted houses, ghost tours, eerie twilight ruins and guided (or self-guided) city ghost walks. If you've got a tale that sent a shiver down your spine, it could earn you a free night away.

The prize on offer is a £200 voucher towards a stay at a Coolstays property. Coolstays lists more than 3,000 properties worldwide, so winners have plenty of choice, from quirky cabins to countryside cottages. The winning tip is chosen by Tom Hall of Lonely Planet, and the best entries will be published in Guardian Travel's print section and on its website.

The mechanics are simple. Tips should run to roughly 100 words, and while you can attach a photo if you have one that fits, the judges are scoring the writing, not the pictures. There's one important catch: for legal reasons, only UK residents can enter. The deadline is tight, too — entries close on Monday 19 October at 10am BST, so you'll need to get your ghost story down quickly.

Even if you don't enter, the callout is a good excuse to think about the darker side of British travel. The UK is stuffed with material for it: centuries-old castles with resident phantoms, plague-riddled alleys on Edinburgh's ghost tours, moody abbeys and lighthouses that look their best as the light fades. A well-chosen spooky stop can add a memorable evening to an otherwise ordinary city break, and ghost walks in particular are an affordable, entertaining way to learn local history you won't find in the guidebooks.

For anyone who has ever done a ghost tour or wandered creepy ruins after dark and thought "I should write this down," this is a low-effort, high-reward opportunity: 100 words for the chance at £200 towards a weekend away. Past winners and previous tips are on the Guardian site if you want a sense of what makes the cut — usually a specific place, a vivid moment and a bit of atmosphere rather than a generic rave review. The terms and conditions are linked from the original article.

Tips via The Guardian Travel.