Calendar File Form: Roger Bell_West has set up a site which converts this page to standard calendar file format, and updates that file periodically. See http://firedrake.org/infobot/ics/conventions.ics for this. Or - I'm told that by using webcal://firedrake.org/infobot/ics/conventions.ics instead, you should be able to "subscribe" to this calendar. Note that I haven't looked at this since this page changed URL.
3rd-5th January: Stabcon 2025, at The Guildhall, 169-171 Wellington Rd South, Stockport, SK1 3UA. A long-running, informal tabletop games convention, which always features some roleplaying. As it is no longer residential, members have to sort out their own accommodation. ("There are several hotels in the area plus various AirBnBs and other options.") Book online through https://forms.gle/cyEkSBWJEzvLLChq6; payment can be made by bank transfer or by sending a cheque or PO. I'm not sure about prices, as they're not on the front page of the form, but last I heard, weekend membership was £20 and single-day membership was £10; however, those values may be out of date by now. Contact bookings@stabcon.org.uk for more information.
22nd-23rd February: Revelation, at The Garrison Hotel, Sheffield."Revelation is a Powered by the Apocalypse and Forged in the Dark tabletop roleplaying game convention... The convention welcomes Powered by the Apocalypse and Forged in the Dark games along with close cousins such as Ironsworn, Candela Obscura or story games." Just a Facebook
13th-16th March: Airecon, at Harrogate Convention Centre. Described as a general "analog gaming festival", but definitely including RPGs, along with a bring and buy, exhibitors, and so on. Ticket prices depend on attendee age and number of days attending. See https://www.airecon.co.uk/home for full details.
5th-6th April: Seven Hills: Generations, at The Garrison Hotel, Sheffield. "Seven Hills is an annual tabletop roleplaying games convention. Born in Sheffield UK in 2014 as one of the annual Garrison Conventions, it offers games inspired by a different theme each year. The theme for 2025 is Generations." Membership appears to be £30. See https://7hills.org.uk/ for full details.
10th-11th May: North Star, at The Garrison Hotel, Sheffield. "Come and play out amazing stories amongst the stars for a full weekend of tabletop Science Fiction RPGs. Avoid Imperial entanglements, set phasers to stun, survive the dark between the stars, or join the crew of the Free Trader Beowulf; whatever path you choose, enjoy some time away in other worlds and new realities for a full weekend." Membership is £15/day. See https://northstarcon.org.uk/ for full details.
30th May-1st June: UK Games Expo 2025, at (I assume) The NEC (Halls 1,2, & 3) and the Hilton Metropole Hotel, Birmingham. Britain's biggest general games convention, with lots of RPG sessions (generally run in the Hilton) among other features. Prices depends on ages, number of days, etc., and aside from the Hilton, there are several convenient hotels for accommodation (though those fill up quite fast). Just an initial announcement so far, but watch the Web site at https://www.ukgamesexpo.co.uk/ for further developments.
28th-29th June: Longcon, at The Garrison Hotel, Sheffield. "An RPG convention for all weekend games. ... Welcome to Longcon, a tabletop roleplaying games convention for long form games that will last all weekend. Fancy a change from high pace 3 hour slots where you finish and want more? Longcon is for you. The organisation of the convention will be a little different, as the all weekend format needs to support people making good choices and organising groups that will play well over the full weekend." Membership rates don't seem to have been set at the time of writing. Watch https://longcon.ttrpg.uk/ for more information as it emerges.
15th-17th August: Grand Tribunal, in Cheltenham (I believe that they use a couple of sites around the town.) "Grand Tribunal is the European convention for Atlas Games' Ars Magica role-playing game. ... Grand Tribunal is a roleplaying, freeform and boardgame convention dedicated to the games and settings of Atlas Games. The convention is of especial interest to fans of Ars Magica, and also Unknown Armies, Over the Edge, Rune and other Atlas Games rpgs. We also have some freeform larp games, but a large Ars Magica themed game suitable for everyone, and some smaller freeforms (in fact the first 'Nordic style' larp run in the UK took place at Grand Tribunal in 2007). ... Grand Tribunal is a small, intimate and friendly event, and while it attracts a number of Ars Magica and RPG authors, it is very accessible to even casual gamers." Tickets are £20 waged, £10 unwaged, with some group and other discounts available. See http://www.grandtribunal.org/wiki/Main_Page for more information.
23rd-24th August: ShadowCon XIX 2025, at Northfields Community Centre, Northfields, London, W13 9SS. An event with some history ("Celebrating over 30 years of gaming"), run by the Shadow Warriors, a West London-based club. Lots of games are promised; price is quoted as "£5 per slot". See https://www.shadowwarriors.co.uk/shadoccon-uk-2025/ for more information, while sign-ups are through https://warhorn.net/events/shadowcon-uk-2025.
11th-12th October: Furnace Games Convention XX, at The Garrison Hotel, Sheffield. "Furnace is an annual tabletop roleplaying game convention ... If you love tabletop RPGs then you'll love Furnace." Registration will open in 2025: watch https://furnace.org.uk/ for more details as they emerge.
24th-27th October: Gaelcon 37, at Crowne Plaza Dublin Airport Northwood Park, Dublin 9. "The Irish Games Association hosts Ireland's oldest independent gaming convention, Gaelcon." No prices listed yet; watch https://iga.ie/gaelcon/ for updates.