First, those old Webleys are much sought after classics, you may want to hang on to them.
Second, There are a lot of choices here. Any reason you don't want CO2? Thats the most reasonable choice here. Your other choices are springers like the Webleys, and pumpers like the Crosman 1377. Unless of course you're willing to spring several hundred dollars for a PCP gun that is. If she can't cock the Webley, pumping a 1377 8 or 10 times will also be tough. Check out the Crosman and Daisy websites for starters.