I would say LSE.

At least not Bristol.

UCL or LSE.

For banking and Finance Law, I would say KCL as a first choice, after that LSE and UCL as a last option (between the 3)

I would choose KCL too because two of the co-authors of Ellinger's Banking Law teach there.

I agree with Interalia. Although you can find excellent teachers at UCL and LSE for banking Law and Finance law modules, KCL has some of the flag bearers in the field:
Prof. Richard Holley and Prof. Eva Lomnicka (co-authors of Ellinger's Banking Law), Professor Ravi Tennekoon (International Finance), Professor Jan Dalhuisen and Dr Tunde Ogowewo (M&A and corporate finance)