Is there a way using script attached to an actor to remove all the actors items but then put them back later ?

The actor will have a set of items so could a form list work ? and if so how could I add items to an actor from a formlist ?

Yes. Create a container (invisible actor), transfer the gear to the container (RemoveAllItems) and when you are ready, transfer it back using RemoveAllItems again. It is a little more complcated if you want to leave the Players current outfit on, etc... but it can be done. You can't remove quest items though... so they will have SOME things. For an example, you could download my mod (Amazing Follower Tweaks), checkout the Quest TweakFollower. It has a fence gear dialogue option that uses an inventory transfer to calculate how much all your stuff is worth. It also has code for remembering and restoring the players outfit.