The steps required to register a ltd company are:
- Register the company with Companies House.
- Sort out your tax with HMRC.
The Business Link web site has lots of useful information. I recommend you read most of this to get a good understanding of the process and (legal) requirements, before contacting the specific authorities to get the official documents and advice on how to complete them.
Beware of issues with insurance, tax, employment status, tenancy agreements and other legal bindings, particularly if registering a company at your home address.
Real World Example
Before you read about how to do it yourself, you might want to consider using a company formation company. This will be more expensive but you'll have to do a lot less paperwork. It'll cost £50 - £100. If you do it yourself (which is easy enough) it'll cost around £15 for the memorandum and articles of association, £20 registration fee with companies house and £5 solicitor's fee for witnessing your signature on the articles of association. Don't forget that it will take a lot longer, mainly becuase you'll need to do a lot of research so that you're sure about what you're doing.
Most of the main banks in the UK offer free business banking to startup companies, for a limited period of course. The decision as to which to choose will be largely dependant on how you expect money to flow in to and out of your account. There are a lot of other things to keep in mind, for example the method of contact that the account will allow (e.g. over the counter, over the phone, via the internet) and whether they offer free business/tax/legal advice.
Most importantly, arrange a meeting with each of the banks and speak to them face-to-face. This will give you a very good impression about how you will be treated once the account is open.
Here is a list of links to the main UK banks that offer business banking: UK Business Banking.
Receiving electronic payments
If you plan to take card payments, whether via a card reader in a shop, over the phone or over the internet, you will need a merchant account. Most banks outsource their merchant services to a third party company. In addition, if you plan to take payments online, you'll probably need to use a payment processor to handle the online transaction.
This means you will have your normal business bank account with your bank, a merchant account with another and an account with an online payment processor. All three of these will charge you for their services.
See this page for more information about merchant services along with a list of merchant service providers, payment providers and the banks that use them: Merchant Services for receiving electronic payments.