Seems a bit of a vicious circle here, doesn't it, I can't picture myself making a putt coz I haven't made a putt of any length for ages...

There seems to be much in having the confidence to eagerly grab the blade from the bag knowing full well that the testing 12 footer you've left yourself is absolutely going nowhere but in the hole...

As opposed to what I do, which is fumble around in the bag for that miserable flat stick and once I find it wonder if I'll actually get this reasonably straight 5 footer I've left myself anywhere within 4 feet...

I read somewhere the other day about a putting drill where you just set up some (6-8 maybe) tee pegs in a circle around a hole on the practice putting green at about 3-4 feet away and then line up 3-4 balls at each tee peg and just go ahead and hole as many as you can in a row. As soon as you miss one, you start over. Self competing I suppose. Trying to build pressure (and confidence) the more in a row you hole.

As you become more proficient, you move further away...

Sounds like it may help...

Cheers