This one came up a while ago (ie you might be able to find something if you go back a few months), the general consensus being that Calais is the cheapest for doing approaches. Now Le2K has an ILS, I imagine they may in a similar boat.
In any case, phone them first, they are all reasonable staff, and will tell you the busy times to avoid so that you can get the most approaches in for your air-time. I can assure you that both EGHH and EGHI will want to charge you for approaches you do, landing or not, but that said, every time I have given my details to EGHI and subsequently done the deed(s), they have failed to charge the credit card!