Can someone go to an experienced CF grad, then to IB?

Say I had two years of experience in audit and wanted to transfer to CF M&A, ultimate goal being IB. How feasible would it be for me to apply to Big 4 graduate programs in the UK? Understanding that their grad programs hire in September for the following year, would there be the chance to join as (for instance) a senior associate, given I'd likely be exam-qualified by the joining date? That would put me back a year in terms of promotions but I'd have absolutely no issues with it, focusing on the long term more.

Asking because it would be an understatement to say off-cycle senior associate hires in that area are few and far between - they're worse than that. Otherwise, I can't see another way for me to eventually get to IB (apart from an MBA).