Internal consulting at fastest growing company in the UK (1000+) vs. MBB

I got an offer for internal consulting with one of the UKs fastest growing companies (profits), w. currently 1000+ employees, with total package at about about 79k-85k USD (relocation, bonus and salary) and the manager says he wants me to take a on leadership role quite soon. I am early in my career with a about 8 months experience from a European Tier 2 firm. At the same time I am also aggressively pursuing other Tier 2 firms as well as MBB where I expect to have a decent chance, at the very least. Should I take the offer for internal consulting or should I pursue consulting firms? What do you know about the prospects of internal consulting? I suppose there is opportunity for fast advancement at this company, though it seems very chaotic.