Autumn is quietly one of the best windows for a coastal escape. The summer crowds have gone, prices drop, and in southern Europe especially the sea is often at its warmest of the year. The Guardian Travel is tapping into exactly that with its latest tip-of-the-week callout: readers are invited to share their favourite seaside resorts in the UK and across Europe for an off-season break — places that stay open after September ends and still deliver plenty to do, plus a decent shot of late-year sunshine.

The brief is straightforward. The editors want recommendations for coastal towns that don't fold up shop when the school holidays finish: spots with restaurants, bars and things to see that keep running year-round. Think of the kind of place where you can walk on an empty beach in October, then find a good table for dinner without booking three weeks ahead.

There's a real prize attached. The winning tip, picked by Tom Hall of Lonely Planet, lands a £200 voucher for a stay with Coolstays, a company listing more than 3,000 properties worldwide — so the reward works whether you fancy a cabin in the UK or somewhere further afield. The best entries will also be published in the Guardian Travel section and on its website, which is a nice bonus if you've ever fancied seeing your name in print.

A few rules worth knowing before you type. Tips should run to roughly 100 words, and it's the writing that's judged — photos are welcome but won't win you the prize. The competition is open to UK residents only, for legal reasons. And the deadline is firm: entries close on Monday 5 October at 10am BST. Terms and conditions are available on the Guardian site, along with past winners if you want a sense of what makes a tip stand out.

Even if you don't enter, the callout is a useful nudge: the coming weeks are prime time for a quiet, cheaper coastal break, and the published tips (once they run) should form a solid shortlist of year-round resorts on both sides of the Channel. And if you already have a beloved off-season beach town you've been keeping to yourself, a hundred words could be the easiest £200 of travel credit you'll ever earn.

Full details and the entry form are on the Guardian Travel site.