You could try www.SHL.co.uk.
Also, go to efinancialcareers.co.uk
I think Kent university also have some test that are open to public. Companies like TalentQ may also have tests on line, but you may have to pay for them.
If you are still in University, then the best bet is to ask career services for help. I am at Warwick, and know that the career service provide, through outside sources, some good quantitive analysis.
On a final note, sometimes doing GMAT practice tests also helps. Although, these are not generally designed for consultancies, but give you good quantitive tests.