There are many kinds of CCTV consultant. Some installers call their sales personnel consultants - they are definitely not independent - they are paid to sell only specific equipment, which may not suit your application. Similarly there are free-lance consultants who have associations with suppliers - you should pay less for the consultancy as normally they get a commission on the sale - but you can pay a lot more for your system as it most likely will include the consultants commission, and the purchase price may not be competitive. Independent consultants, who are independent, is the best bet. You may see more expense initially on the table, but you will know where you stand, and there should be no surprises down-line. It takes guts to be an independent security consultant with integrity, so look for one where they have been vetted by their peers and abide by an acknowledged code of practice. The only professional organisation in the UK founded solely for independent security consultants is the Association of Security Consultants (ASC).