I want to protect my company name but do not want to be limited and trademark application v expensive I was told about this company http://www.nationalbusinessregister.com/ but since been advised that rules have changed and that you can only protect through limited status is this correct?
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Why don't you register the limited company name and just leave it dormant?
It doesn't have to be used, just make a declaration each year to Companies House that it is dormant.
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From what I can see, Nation Business Register allows you to register the company and thereby protect the name.

As far as I know a company name is either available or not. It is not possible to “reserve” it unless you are actually in the process of incorporating it.

Online company formations can cost ?5 and provided it remains dormant, the only additional costs are the annual return fee to Companies House. Dormant company accounts can be filed free online and require nothing more than a few entries.
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My understanding is there is no official register as such so what does the National Business register really do for you?

Under present UK law I believe it is more important to look more that businesses are not "passing themselves off" as others ie pretending to be someone else.

Forming a UK limited company with your trading name will stop anyone else setting up a company with a similar name to yours. I am sure Vicky can explain that many dormant companies exist just for name protection reasons.
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