Advice for a graduate

I graduated in July from a non-target (top 30) university in the UK in Economics. I have been constantly changing my mind about which career to pursue. When I first started university I considered IB however the hours put me off. I didn't have much luck with spring weeks or internships and ended up with a placement in marketing.

I only started developing a keen interest in strat consulting whilst on placement. MBB is a long shot however I was wondering what firms I could apply to given my background. I will consider LEK, RB, ATK, Arthur D Little, and the big 4 which is my best bet.

But outside of pure strat firms what other options are there. I aim to work for a few years and then hopefully get an MBA at a top B school and make the transition to MBB. With regards firms such as PwC and KPMG is it better to secure a role in M&A even though I want to work in strat eventually. Is M&A at a boutique an option?