A second opinion

I have a client for whom I am preparing a VAT Clearance application at their request. There is a significant amount of tax at stake here and I wish to secure a favourable result for my client. I am seeking a second opinion of the argument I am constructing and would like an external party to undertake a hot file review. I reckon a second pair of eyes would be rather useful.

Anyone out there provide this service or know of a Firm/Chambers that does?

EDIT: I am preferably looking for an individual consultant/Chambers.. someone who is not interested in my Compliance work !

Cheers,

Chris