PS Grad, as I am not from UK, could you expand upon what u mean by 2nd Tier?
Whereabouts on a national ranking is that, 20-50? 50-100?
I'm not a top-tier strategy consultant, but someone who was frustrated by the holy grail of joining a top strategy firm for a couple yrs, which I have since overcome never having succeeded. So, knowing that, you can take or leave my advice on what you should now do.
1) Be clear on whether you want to work in strategy consulting, or just MBB. (I know u never mentioned MBB, but ppl seem to have led the discussion down that road)
2) If you decide on the former, be careful about what you consider as a "top" firm, and set your sights/scope accordingly. If you let ppl convince you top = MBB only, you may have a frustrated few yrs ahead. But in the grand scheme of the consulting world -from boutiques to IT firms, accounting firms, corp finance houses; global, international and local- I think you can consider many other firms as being "top". Of course ATK/Monitor/RBerger/OC&C ... but the strategy practices in Big4, ACN, PA also all work with big clients, in many countries, hire smart people (queue laughter from the Oxbridge+Harvard MBA snobs), will challenge you, are well known, and will open many doors down the road.
3) Match the financial resources and time you have available with your answer to Q2. If you only want to work in strategy consulting to get a really tip top name on your CV (ATK, Monitor et al), you'll need an MBA from Insead or LBS. If you can't pay for that, forget it and move on. Then of course that may only get you an interview, not a job.
If you'd be happy in the Big4 grouping, an MSc from a really good business school should at least get you an interview, as a degree in Economics is a solid base, regardless of the Uni. And even if those interviews don't materialise into jobs, you'll be in a good position to join a good company in Industry.
I have a degree from an extremely mediocre institution + a fantastic MSc. Over the yrs I've managed to get (unsuccessful) interviews with Monitor and Berger, among others. I now work in strategy for one of the world's most admired companies, and I wouldn't change my lifestyle for any consulting firm.