Does anyone know of a free piece of software which will enable me to merge two pictures together to form one long picture i.e. I took two photos of a large scene and want to put them together to make one large scene?
What you are asking is beyond the scope of most image editors without a lot of work, because hues are certain to differ in the adjoining photos. Software that does the job properly without any hassle is very expensive. I use this one click here
You can do it PSP using the method suggested by Yoda Knight, but, as I said, you will have a lot to do to make the resulting image look natural.
I can't comment on Photosuite because I've never used it, but to be honest even Photoshop requires that a lot of editing be done when merging is attempted. Of course it can be done, its just that Stitcher does it much more easily.