I've made Silver this year in just three TATL r/t in WTP with UK domestic legs attached (so 220 TP per r/t).
I've actually done more flying than that, with some more WTP legs but also discount Y which has me currently on 895 TP with a TATL WTP out, CW back booking to come over Christmas that will put me on 1125 TP by the end of the calendar year.
With my TP year ending on April 8th I have a decent chance of making Gold.