UK spring scheme advice for a humanities student going to a target

If results day goes well I should be going to the LSE for a humanities subject that has little directly to do with Econ or quantitative stuff. Aside from corporate law and consulting, I've started considering finance springs as well. 

(1) My first preference atm is corporate law followed by finance and I'm wondering if it's possible, time-wise (and balancing this with the social and other aspects of starting uni) to apply to finance + law springs, possibly consulting as well

(2) On finance specifically: my worry is that my knowledge of technicals is weak. Ik behaviorals are more common in springs but if anyone has experience if hirevues, interviews and so on it would be great to know what level of technical knowledge I need. I've started  trying to self learn the  basics e.g. sell-side, buy-side, beta, WACC, the three statements over the past week. If anyone has any advice on this front I'd be massively grateful 

(3) I've got a CV mostly done now and I'll start working on cover letters soon - when did people start prepping for physcometric and situational judgement tests? Jobtestprep looks expensive and I don't want to take out a subscription until I have to.

Thank you in advance!

.