It’s more costly both in terms of time and money to trade as a limited company.
First up, you have to pay to form your limited company. If you do it yourself, it can be as low as £20, but if you get someone to do it on your behalf, it can be as much more.
You have to keep proper accounting records (but of course, you would be doing that as a sole trader!), but with a limited company, you will have to provide a set of end of year accounts to Companies House.
Other people, including your competitors can see your accounts and other information that you are obligated to file at Companies House.
If you are over the audit threshold, you will also have to pay to have an audit.
If you are looking for finance, lenders may ask for personal guarantees, possibly with your house as collateral. If that’s the case, how limited is your liability, anyway?
You will have to deal with Corporation Tax as well as your personal tax situation.