What is the S.A.S? And can you just sign up for it?

Good Morning and thanks for your question, The SAS is the abbreviation for the Special Air Service. One of our special forces units. It is an incredibly demanding role and requires a very large amount of training prior to attempting to join. There isn't a huge amount of information on what exactly you will be doing, due to the highly sensitive nature of the work they do. But you can expect a very demanding yet rewarding lifestyle that covers a range of skills and qualifications. You can't join the SAS straight from civilian life, you have to join the Army first and then serve a minimum term of 4 years before attempting the Special forces selection process. You can do this from anywhere in the army, but some units will give you a better chance, such as the Parachute regiment due to the similarity in their job role. It's an incredibly difficult role to get into, but it's achievable, and if you want to set your sights high then I would always encourage you to go for it. The training you undertake from your time in the army will set you up to give you the best chance of being successful. The focus will be highly on fitness, so being able to move quickly across a large area, and carrying a large amount of equipment as one example. As well as this, there are many other tests you will have to get through to be successful. Further information on these will be given if you express your interest once you are eligible to join. I hope this helps, if you have any more questions then don't hesitate to ask.

Is there a limit on how tall you have to be?

Generally no, As long as you meet the criteria for joining the army in terms of height requirements, then you should be absolutely fine.