Yes, Atthe is right - they will test both you and your partner for chromosomal problems, your progesterone levels, possibly clotting factors, and they will most likely do a scan to check your ovaries and uterus. All in all, it took about 6 weeks after the last test, before we got the appointment to discuss the results.
However, in most cases, they do not find anything. I've now had 4 mcs, 2 of which were tested, and both were due to chromosomal abnormalities (trisomy 2 and 18) of the baby. DH and I are both fine - apart from our age!. It's the most common cause of miscarriage, and there is nothing that can be done about this.
So no success for me from the testing - other than knowing that nothing is wrong with either me or DH (should be a good thing, really...). And the hope that we might get lucky next time...
They might recommend that you take progesterone, should you become pg again, but this is the standard first line of treatment, people are not entirely sure if it really makes a difference. If any clotting issues are found, you will get heparin.
Sorry I can't shed more light - Lesley Regan's book is very informative, definitely worth reading.