Hi Laundrymonkey and welcome to the Xperia Support Forum! 
I am very sorry to hear about you losing the unlock pattern in your Xperia phone. There is two ways to go in order ty bypass the screen lock and get access to your device. However, both of these measures will delete all personal data in your device.
If you have access to a computer you can connect your phone using the charging cable and perform a software repair. Option number two is that you can use Google's service Find My device in order to perform a factory reset of your device. Just log in with the same google acount that is synced in the phone and select the option named Erase.
Let me know how it goes and have a very nice day!
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