My DS1 did this course. He started A levels, but by half way through Y12 it was obvious it wasn't going well, shall we say! I worked as a HCP with another person with the same HCP degree as me who said he'd got into uni with a 3 A level equivalent Applied Science Extended Diploma BTEC, so I researched them and discovered the one in computing.
It was a very different experience to A levels! It was run at a Tech College, rather than sixth form; the course was 9-3 Mo-Fri, no 'frees'; eight students in his year.
As you know, BTECs work on continuous modular assessment; not final exam. DS1's did have 4 external exams over 2 years, introduced to bolster the academic credentials of the course, but the other 9 modules weren't examined as such. So it was a different way of working.
Anyway, DS1 got 2 x D starred and 1 x D, and is now in his third year at uni doing Computing (actually a paid year 'working in industry' in a company that has a habit of employing them after uni!).
Now, here's the thing: In our opinion, the BTEC was easier than some A levels might have been (but not all!). He did have to 'keep it up' tho there was more leeway in 'deadlines' than we were lead to believe.
Regarding Computing, be aware of the difference and blurred lines between 'Computing' and 'Computer Science' degrees. Know that you are unlikely to get into a RG to do CS even with a top-marks BTEC as they will want a Maths A level at a high grade, too. DS has found that even with his 160 UCAS points, out of a top score of 168 (like 3 x A star A levels); he wasn't able to get into top flight unis, tho most RG do CS not Computing. He could have got on his (ex-Poly) course with BBC grades.
However, also note most employers don't care where your computing degree came from (as long as it wasn't from a really low-rent establishment!). Check the league table position of the course. Also, be aware that if your DC has a BTEC in the subject, the first year at uni will be easier for them than for those entering with A levels, other than maybe Computer Science A level, having done nothing but study that subject at BTEC for the past 2 years.
Finally, the BTEC is an employment ticket in its own right, unlike A levels!
My second DS actively chose a 2 A level equivalent BTEC alongside an A and AS level (then an Art Foundation year) because he knew what he wanted to do, at 15. He's now in his first year at uni on the most highly rated course for his subject in the country.