Ideation
Come up with an idea and a plan. Read the ideation article on this site, and those in the Useful Links, especially the Y Combinator articles. Determine if this really is a good idea by going through the Business Plan template and answering all the questions it asks in conjunction with the articles in the Plan section of the website.
Prototype
Start cheap. Build a beta of the website, or even just a front end that has no automation behind the scenes and requires you to manually do everything. Get some customers, to prove there is a need and to learn about the market and price it will pay. If it’s a physical product, make a prototype out of something.
Check Names
There are three places you will need to register your name, so make sure it is free in all of them before you register one and then find yourself stuck.
For your legal company name, go to the Companies House name checker. Remember, this is just the legal name of your company, not the trading name. You can register as 123 Ltd for Companies House, but trade under “Happy Med” for your customers.
For your website, you need to go to a domain checker. There are lots of these, including wordpress if you intend to build the site there, ionos if you want to register there, GoDaddy, and others.
For the trademark, remember it costs different amounts to get a trademark for different regions (UK, EU, others). Check them on the government site.
Register a Company
It costs £12 on the Companies House website, and takes about 30 minutes. Your company will be registered within 24 hours. Unless you already have a team, you can appoint yourself Director and Secretary, and issue all the shares to yourself.
Each share has a value that you can assign; £0.01p is fine. You can always issue more in future. You probably won’t pay the money you owe to the company right now, so if you issue yourself 1,000 shares for 1p each, you owe the company £10, as your shares are not Paid Up.
Consider that when you take on employees and investors, you will need to issue them new shares according to percentages agreed: so it’s better to have at least a thousand shares, or accurately getting to the percentages will be tricky.
You will have to give your address and the company address, the latter of which is on the public record. That will probably be your personal address to begin with, but if you don’t want to provide that then you can use a lawyer or accountant to host your company address, or a virtual office space.
Register a Domain
This can be done in any of the places you used to check for availability. Register a few variations; .com, .co.uk, .org, and so on, as you don’t want people setting up sites on similar domain names to you once you have customers, and then absent minded customers landing on their pages, not yours.
You do not need to start using your new domain as an email address early on. Just put up a landing page as and when you think it is necessary, and leave it at that; there’s a good chance that you’ll get rebranded in the near future anyway and so will need a new domain.
Register a Trademark
This is especially important if you are going to be a B2C company. I would wait with this step until much later on though, again because you may rebrand. It costs £170 online and can be done on the government website.
Branding
Keep it simple until you have a product. A graphic designer costs from a few hundred pounds to a few thousand, whereas a branding agency will usually begin at around £5,000.
IP Plan
Most entrepreneurs are convinced that one day a lawyer will wave an IP wand and thenceforth competition can be struck from the business plan. Most investors give IP a near-zero weighting at the startup stage (it changes later on). Don’t spend money for now. Once you have first investment, perhaps go to an IP lawyer for an IP plan. And once you’re big enough to need to implement that plan, your investors will be doing it with you.
Maintain Your Company
You will need to file an annual return with Companies House, and a Confirmation Statement with them once per year just to state any major changes to your company’s ownership and appointments. You also need to file your accounts with Companies House. If your company hasn’t set up a bank account and begun trading, then you can register it as dormant. This means you don’t have to file any accounts.
You also need to file accounts (tax returns) with HMRC, and it is HMRC you tell if you are dormant (you don’t have to tell Companies House until your first return).
You can pay an accountant to become your registered agent, which means that they will deal with all of the annual filing for you.
Conclusion
You can have a company and domain set up within 24 hours for less than £15, but there’s no need to do so until you have been through the ideation phase, come up with a credible plan, and now need a company to interact with either an investor, supplier, customer, or employee.