How to organise a speedcubing competition
The World Cube Association is the main governing body for speedcubing competitions worldwide, the UK's regional organisation is the UK Cube Association, speedcubing.org does not organise speedcubing competitions but merely supports the organisation of competitions through sponsorships and promotions of such events.
If you would like to organise your own speedcubing competition then it is advised that you first attend a few of them so that you have experience competing, there is now one almost every weekend somewhere in the UK so keep an eye out on the World Cube Association page to stay up to date with the latest announcements, make sure to check the registration date as some of them do fill up very quickly, I would generally advise being ready to register at 7:00 PM on the day of registration to ensure you get a spot!
If you have experience with competitions and are ready to try organising one then you first need to find a venue, school and leisure centre sports halls are usually excellent options but they do need to be free the entire weekend, the UKCA would require the venue to be available from 8:00-19:00 on Saturday and 8:00-18:00 on Sunday. The other thing to be aware of is the cost, the UKCA charges £30 for a 2 day competition and usually £10 of that is required for general expenses so the venue should not cost more than £20 per competitor. Competitor limit can be determined by dividing the area in square meters by 4, if we have a hypothetical venue that is 23x32 meters, obviously 23x32=736 and 736/4=184, if the venue costs under £3600 to hire for the entire weekend then it can be considered, some venues are significantly more expensive than that so the UKCA will not use them. One other factor to consider is the location, it is generally best for the location to be near good public transport links and with good accommodation and shops nearby.
If you have found a suitable venue then you can see whether they have availability on dates where other competitions are not already scheduled, the UKCA have a planning calendar to help with this, sometimes the UKCA does run multiple competitions on the same weekend but they are usually in different parts of the UK, it is also a good idea to plan for a date a good few months away, the UKCA regularly plans competitions the furthest in advance in the world!
If you have a suitable venue you can contact the UKCA to begin the organisation process, the UKCA delegates will then support you in the rest of the organisation process.
Organising a speedcubing competition is a lot of work and you will probably find that your results in the competition itself are worse than at previous competitions as you will have less time to warm up and more stuff to think about but it is very rewarding and looks good on your CV.