In my view it is worth giving some thought to the domain name(s) for your site. It is often the first information the public will learn about your business, and from it they will develop their first impression of you.
Ideally your domain name will be the same as your trading name, but there is no guarantee that such a domain name will not have already been taken by another organisation.* If possible it is worth getting at least the .com and .co.uk versions of your trading name, as these are the ones which most people will type into their browsers as a trial if they are not aware of the actual web address of your site.
Where the .com or .co.uk top level domains are not available it is still quite possible that you will be able to use your trading name - by accepting more unusual top level domains, such as .biz, .tel and .me. Many major companies, however, are content to accept domain names which are only distantly related to their trading names.
There is no reason why you should not have multiple domain names, all taking the visitor to your same website. In my case, for example, workofdata.net, .com, and .co.uk all take you to this site.
Work of Data will obtain and/or manage domain names as your agent at very reasonable rates.
* NB Limited companies and PLCs have the top level domains .ltd.uk and .plc.uk respectively reserved exclusively for their use, provided that they use only their registered name in the domain. These are used so seldom, however, that few of us know of their existence, or would trial these addresses if we did not know the actual web address of the company.