I'm new to salesforce and am working on a developer edition while I'm learning how to use it.
I have created a Visual Force page as per one of the tutorials. It works when not on the public site.
It's just a list of contacts with a filter and pagination functionality.
When I put it on the public facing site, the initial list shows fine, but when I try any of the functionality, I just get a blank page.
From the browser console, I get the following errors:

Loading failed for the <script> with source “https://butch-developer-edition.eu16.force.com/jslibrary/1530643972000/sfdc/VFState.js”.

Loading failed for the <script> with source “https://butch-developer-edition.eu16.force.com/jslibrary/1530643972000/sfdc/main.js”.

Loading failed for the <script> with source “https://butch-developer-edition.eu16.force.com/jslibrary/jslabels/1537578900000/en_US.js”.

ReferenceError: GenericSfdcPage is not defined

ReferenceError: MenuButtonRounded is not defined

Loading failed for the <script> with source “https://butch-developer-edition.eu16.force.com/jslibrary/1530643972000/sfdc/MarketingSurveyResponse.js”.

ReferenceError: setFocusOnLoad is not defined

ReferenceError: closePopupOnBodyFocus is not defined

So it looks like some sort of permissions issue for the guest profile, but I have no idea what.
The public facing site is at https://butch-developer-edition.eu16.force.com/
The source code for the page is:

<apex:page standardController="Contact" recordSetVar="contacts">
  <apex:form>
    <apex:pageBlock title="Contacts List" id="contacts_list">
        Filter: 
        <apex:selectList value="{! filterId }" size="1">
            <apex:selectOptions value="{! listViewOptions }"/>
            <apex:actionSupport event="onchange" reRender="contacts_list"/>
        </apex:selectList>

        <!-- Contacts List -->
        <apex:pageBlockTable value="{! contacts }" var="ct">
            <apex:column value="{! ct.Name }"/>
        </apex:pageBlockTable>

        <!-- Pagination -->
        <table style="width: 100%">
            <tr>
                <td>
                    Page: <apex:outputText value=" {!PageNumber} of {! CEILING(ResultSize / PageSize) }"/>
                </td>
                <td>
                    <apex:commandLink action="{! First }" value="« First" rendered="{! HasPrevious }"/>
                    <apex:commandLink style="color: #ccc;" value="« First" rendered="{! NOT(HasPrevious) }"/>
                </td>
                <td align="center">
                    <!-- Previous page -->
                    <!-- active -->
                    <apex:commandLink action="{! Previous }" value="« Previous" rendered="{! HasPrevious }"/>
                    <!-- inactive (no earlier pages) -->
                    <apex:outputText style="color: #ccc;" value="« Previous" rendered="{! NOT(HasPrevious) }"/>
                    &nbsp;&nbsp;  

                    <!-- Next page -->
                    <!-- active -->
                    <apex:commandLink action="{! Next }" value="Next »" rendered="{! HasNext }"/>
                    <!-- inactive (no more pages) -->
                    <apex:outputText style="color: #ccc;" value="Next »" rendered="{! NOT(HasNext) }"/>
                </td>
                <td>
                    <apex:commandLink action="{! Last }" value="Last »" rendered="{! HasNext }"/>
                    <apex:commandLink style="color: #ccc;" value="Last »" rendered="{! NOT(HasNext) }"/>
                </td>

                <td align="right">
                    Records per page:
                    <apex:selectList value="{! PageSize }" size="1">
                        <apex:selectOption itemValue="5" itemLabel="5"/>
                        <apex:selectOption itemValue="20" itemLabel="20"/>
                        <apex:actionSupport event="onchange" reRender="contacts_list"/>
                    </apex:selectList>
                </td>
            </tr>
        </table>
    </apex:pageBlock>
  </apex:form>
</apex:page>

Can someone point me in the right direction please.
I'm using the Summer '18 release and only using the lightning interface, so not familiar with the classic interface at all, so please hold my hand if giving me replies that involve classic.