Hi Alasdair, I am a Titleist staff player and an advanced Titleist fitter, based in Exeter. I think your starting point should be to establish the loft on your existing pitching wedge. e.g. if it is 48 degrees, then consider 52, 56 and 60. if you only want two wedges, in this instance I would suggest 52 and 58 degrees. The next consideration is going to be the bounce on the wedges (very important). I will deal with each wedge in turn.

Vokey offer 8 and 11 degree bounce in the 52 degree wedge, the 12 degree bounce will launch the ball slightly lower (This could be a consideration particularly if you're playing in those windy links conditions). When considering the bounce on the 56 degree sand iron, you need to consider whether you have a steep angle of attack - the steeper the angle, the more bounce you will require and would suggest you get your local Titleist Pro to get you to hit a few shots off of a skid board to establish the correct bouce. As for the 60 degree, the same applies but considering you play mostly links golf, I would probably suggest a little less bounce than the 56 degree in order to help you play the ball off those tight lies!

Hope this helps!