CombinedResultField (Type Text) = EstateCode & Estate_Number
And on a layout, you can keep the data in separate fields, but display them merged together by using merge text:
Enter layout mode, select the text tool and click the layout where you want these two merged values.
Select Merge field from the Insert menu twice, selecting these two fields in turn.
This produces this text in layout mode: <<TableName::Field1Name>><<TableName::Field2Name>>
In browse mode, you'll see the two values merged as though you have a single field--though this is for display only, you can't edit merge fields.