Hi Duncan,
If there are not the SRV records, you cannot communicate with external users such as Lync users in other organizations and Skype users signed in with a Microsoft account. If only communicating with internal users can meet your requirements, you can ignore the SRV records.
If not, here are two optional methods:
1. Since you cannot add the SRV records by yourself, it is recommended you contact the DNS hosting provider, and let them help you add the records.
2. Or you may want to consider changing another DNS hosting provider.
Thanks,
Tracey