as mentioned, VAT is not just for Ltd companies, it is based on turnover not company status, even if you don't register as a Ltd you still have to register for VAT when you hit the current year's threshold.
The main benefit of Ltd for a small outfit is that the company becomes a separate legal entity which you would own / co-own, in the event of any serious issue the legalities would be against the company rather than you (although if you commit any very serious issues you could still be personally liable so it's not a complete get out of jail free card).
A VAT registered Ltd will generally be taken more seriously than a sole trader by other companies.
If in doubt go and speak to your accountant or financial adviser who will be able to give you proper advise.