Is a master's degree more suitable and cost-effective than a bachelor's degree for my situation in UK?

A master's degree is generally more suitable for you, given that you already hold a master's in International Business. Pursuing another bachelor's would not add significant value at your education level.

However, a second master's abroad can be costly - £15,000 - £45,000/year for tuition in the UK, plus living expenses of £13,761 (London) or £10,539 (outside London) for a 9-month year. The career benefits may not always justify the investment unless you need international recognition or specialization.

Consider professional certifications or short-term courses for better cost-effectiveness, unless you have a clear reason for a second master's.