Don't join midpoint.
It has never been standard procedure. Well, not since 1975. It would have to be one hell of a wind for a C152 to make 800 ft aal by the upwind numbers. Level at 400 aal on climb-out or go-around in orderto miss the 800ft crosswind leg traffic over the upwind numbers.
I was once given a telling-off by an Examiner when on a renewal at Blackbushe for joining over the 07 numbers. He said that it wasn't the C152s that were the problem but the high-performance a/c like the B200 etc that could well intersect with you and that a mid-point join was SOP. This was about 15 years ago.
TheOddOne
ps
Royal Electrical and Mechanical Engineers (REME)
??? New to me, thought it stood for 'Rough Engineering Made Easy' or 'wReck Every Machine Eventually'
Hat, coat, etc