Amy
Shortly after I found out about my MMC last summer, I ordered some cheap ovulation sticks off Amazon- think they were OneStep or something.
I had never used OPKs previously (2 pregnancies) but I wanted to make sure we had a "good start" to conceiving in case it took a few months (!) as opposed to straight after stopping the pill before.
They did seem to work for me, getting what I thought was a positive around CD14/15 although I was never quite sure as it is quite open to interpretation.
Anyhow, absolutely bugger all happened apart from positive OPKs and back at the start of this year, I was feeling desperate so I ordered a Clearblue dual hormone kit from Amazon. v expensive- 20 sticks for about £28, came with stick holder which gives you the reading.
I liked the CB tests as you either got a negative (clear screen), high fertility (flashing smiley) or peak fertility (static smiley). always got a static smiley on CD14 or 15 which correlated with the cheap OPKs.
Would love to say the they CB kit changed everything and I fell pregnancy straight away, but sadly not!
From January to March this year I used the sticks until they ran out, we continued DTD as we always did- every other day during fertile week, work schedules allowing. Didn't order any more when they ran out- there was no point.
Also, I chucked the holder/reader in the bin last week in a fit a rage 
sorry such a longwinded reply...that's my experience of OPKs!
I would recommend them, but maybe splash out on a more sophisticated one for the first few months, so that you can be sure of your fertile days for a few months.