Please don't apologize. I also ask for help plenty of times.

The fault is mine. I forgot to include that you need to also create a setter. Unless you need to do some processing of the value when setting, which I don't think you do in this case, use the following when specifying the field

Integer minNumNights {set;}

this will create a default setter to allow you to set the variable.

Still having problems but have changed a bit of the code.  I think the read only problem was because I was not using the right type.  Now I can render a field and if I hit enter with or without a number the query runs but it only brings back the default minimum so it's ignoring the field but it seems like progress.

To be honest this query came from somebody that want a quick solution.  I have now built a report which is a temporary fix and buys me a few weeks.

Here is the VF page

<apex:page controller="Resmanager">
    <apex:sectionHeader title="Availability Search"/> 
        <apex:form >
             <apex:pageBlock mode="edit" id="block"> 
                <apex:pageBlockButtons >
                </apex:pageBlockButtons>
                <apex:pageBlockSection >        
                    <apex:pageBlockSectionItem >
                                <apex:outputLabel for="searchText">Amount of Nights</apex:outputLabel>  
                                <input type="number" name="{!minNumNights}"/>  
                    </apex:pageBlockSectionItem>
                </apex:pageBlockSection>
                </apex:pageBlock>    
              <apex:pageBlock title="Reservations">
                  <apex:pageBlockSection >
                        <apex:pageBlockTable value="{!Reservations}" var="res">
                            <apex:column value="{!res.Start_Date__c}"  />
                            <apex:column value="{!res.End_Date__c}"  />
                            <apex:column value="{!res.Nights__c}"  />
                        </apex:pageBlockTable>
                   </apex:pageBlockSection>               
               </apex:pageBlock>
     </apex:form>
</apex:page>

And the APEX code

public class Resmanager {

    Integer minNumNights {get; set;}
    Integer mnnDefault = 4;

    public Integer getMinNumNights() {
       if(minNumNights == null)
          minNumNights = mnnDefault;
       return minNumNights;
    }   
        
    public List<Reservation__c> getReservations(){
        List<Reservation__c> listBd=[select r.id, r.Start_Date__c, R.End_Date__c, nights__c from Reservation__c r where nights__c = :minNumNights];
        return listBd;   
    }
   
}

Thanks again for all your help.

Cheers R

Thanks again for all your help got there in the end.