I managed to figure out a solution myself over the weekend and did it
different to the suggestions. So for anyone else having the same
problem, here's how I solved it:

NB I have only been learning VBA for a week so this may not be the
best way to do it!!

Private Sub Type_Change()
If Type.Value = "Option1" Then Product.RowSource = "Option1List"
If Type.Value = "Option2" Then Product.RowSource = "Option2List"
If Type.Value = "Option3" Then Product.RowSource = "Option3List"
End Sub

Where the Option?List is a named range in the spreadsheet.

Please if anyone has an opinion on this method then let me know cos I
am just learning!.