The danger with the Smiler queue line is that unlike other queue lines, eg, Rita - it is below the level of the ground thus eliminating any breeze or air through the queue, and secondly, its surrounded by concrete which causes an intensity of the sun around you. Add to this a feeling of being "closed in" and you have a recipe for disaster on hot summer days.
Perhaps they should invest in some panels over the top of some of the queue line areas to provide some shade as you slowly move around the queue - and there need to be access points for staff, and exit points for people waiting if there is an emergency. With Rita and other similar queue lines - at least to some extent you have the option of climbing over the fence and/or shouting at the staff near the entrance to attract attention.
Hope you are ok T and wish you a speedy recovery.