请问windsor package 是怎么买的

看到板上有老人说这样连火车和门票的package不仅省钱还省排队买票的时间，心动阿。但是查了southwest trains的网站，还是不太明白怎么买，是要到服务中心一起买火车票和门票吗？还是可以先在网上买好advance的火车票，再拿火车票去旅游中心买温莎堡的门票？多谢。

火车网页上的说明如下：

Find out how much you can save when you buy a combined rail and entry ticket to Windsor Castle. Just add the combined ticket price in bold to the cost of your rail ticket to Windsor & Eton Riverside or Windsor & Eton Central. You can find the cost of your rail ticket by using our online journey planner.

You can but combined rail and entry tickets from our Customer Service Centre or from any staffed train station. Make sure you buy your combined rail and entry ticket before you get to Windsor as Windsor Castle can only sell you entry at the 'on gate' price.