Hiya,
A mate on my course at MYT ws in the same position.
He started the crew training course becuase eh couldn get a pilots job, and is currently flying long and short haul with MYT as Cabin Crew and is loving it!
Its really good to learn how the other part of the cabin works, and also gives you a headstart in CRM.
The height restrictions are usually (depending on a/c type) 5"4 - 6"2.
Weight in proportion to height.
Hope this helps, go for it!