If you employ people you need employers liability insurance, if you drive you need motor insurance, these are usualy the only REQUIREMENTS, but yes, you would be wise to have PI in this line of business. You might also want to consider public liability if people visit your premises, I'm guessing you don't make or sell anything tangible so product liability you probably won't need.
As for suppliers, not my forte, maybe some self-employed types can suggest. Alternativly Aon, Marsh and Willis are the biggest isurance brokers and will probably get you quotes or you could just phone round a few brokers from the Yellow Pages.
It's important to have enough cover, get at least £5m, but bear in mind if your negligent advice causes a loss it could be more than that, depending who your are advising. Ultimatley, if you don't have enough cover, unless you have lots of assetts you're probably not going to get sued.
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This is not legal advice. If you want legal advice consult a lawyer.
