Singaporean applying for Mathematics in the UK - are my grades good enough?

Hey there!

Name's Ivan. I'm applying for Uni in the year 2017 - that is, I'm planning to apply for 2016's entry, then apply for deferment, a double hurdle. The gap year isn't entirely my choice, since I'm spending it in the SAF for my National Service.

I'm very confused by the entry requirements, and using the 'Net to source for information on 'converting' the standard A level offers to Singapore's GCE A Levels is rather confusing. My grades are below:

H2 Mathematics: A
H3 Mathematics: Merit
H2 Physics: B
H2 Chemistry: A
H1 Economics: A
H2 Knowledge and Inquiry: B

Link to syllabi for each subject:
http://www.seab.gov.sg/pages/nationalExaminations/GAL/School_Candidates/2015_GCE_A.asp

As far as I know, the equivalent of H1 is AS level, and the equivalent of H2 is A level. I'm assuming that my three grades for A level would be AAB then.

I'm thinking of applying to Warwick, Durham, St. Andrews, and ICL, but I realise that I'm being too optimistic about my chances of getting in. I'm taking the STEP II/III test and IELTS in 2016, but I'd like to know my chances (and if my grades are good enough).

Also, recommendations for insurance choices would be much appreciated!

Thanks!