I have an unconditional offer for Law. I took English Lit, History, Maths and Biology - similar to yours. You should be absolutely fine.
For the LNAT the only way you can really prepare for it is by completely sample tests on the LNAT website. For the essay section of the LNAT you should make sure you read a newspaper everyday for a couple of weeks before taking it, to familiarise yourself with the writing, which is similar to how tsecrets ions in the test are written.
To be honest though reading a newspaper is not entirely necessary.