Luke, for the current programme they made it very clear what the requirements are:
either 3 A-Levels at Grades BBC or above, excluding General Studies.
or an Honours Degree at 2:2 (or higher) or a pass (or above) in a higher degree such as MSc, MA, MPhil, DPhil, PhD, MBA.
If you have equivalent academic qualifications then you will be asked to provide a Letter of Comparability from UK NARIC before attending your first selection day. The Scottish educational qualification equivalents are detailed in the FAQ page.
There is no mention of equivalent English qualifications (BTEC). It is rather clear cut.
You can only use NARIC if you have qualifications outside the UK. So unless you call them yourself, the answer is no.
Of course next year, if BA do run a FPP, then the entry requirements may have changed, it could be harder even.