You can also add a sleeve to pretty much any bag pattern you like. Since there will be some stress on the sleeve, use an iron on interfacing to strengthen, then add a lining. Make sure that the space between the stitching is at least the width of your trolley handle plus 2 to 4 inches for ease. So the bag doesn't flop forward, I would make it about 3 inches shorter than your bag, centering it so there's about 1.5" at the top & bottom.
It's easiest if the handles extend to the bottom of the bag, just sew the sleeve between them, adjusting the space between the handles to accommodate the sleeve. If the handles are just at the top, cut your sleeve to size (remember to add seam allowance!), iron on the interfacing. Cut a lining the same size. Sew the 2 pieces, right sides together, around all the sides, leaving an opening to turn. Turn right side out and top stitch around the edge, then add to the back panel of your bag. Make sure you secure the top & bottom of your stitching lines by reversing a couple times.