Katylux most appointments do happen from 2nd trimester / second half of your pregnancy as nothing can really be done to save baby in the first trimester... From about 20-25 weeks on you should be seen every 2-3 weeks (if not more often if per se baby is breech or something else concerns the midwives).
Under the hood exams don't really happen unless necessary. ie) You have a bleed at anytime during pregnancy they'll do an exam and take swab samples, possibly doing an internal untrasound if a regular ultrasound (is needed and) can't determine where the bleed's coming from, for another medically necessary reason...or if you have any known cervical issues. Also, if you're under OBs care they may do an internal when you're closer to your due date to see how your cervix is softening and you can expect to get a sweep (or 2) from your midwife or OBs when you're overdue. Otherwise they try to just leave your pregnancy to progress as naturally as possible.
Chrissy - most bloodtests are optional and they should've explained this to you at your booking in appointment if not given you a booklet in your Bounty envelope that explains all the blood tests offered during pregnancy. I believe the 16 week blood test is for Downs syndrome and possibly the HIV test as well if I'm remembering correctly.
Here's a basic timeline / guideline I found from the NHS for Antenatal care:
http://www.nhs.uk/Planners/pregnancycareplanner/pages/Antenatalcare.aspx and another for checks and screening:
http://www.nhs.uk/planners/pregnancycareplanner/pages/Checksandtests.aspxI agree with Cadenza that Baby Centre's an invaluable source of information from inane little things to major problems explained in a pretty easy manner with links to more information if necessary. There are 2 sites: US & UK so information is more country-specific and accurate to your pregnancy. They both have forums you can chose to participate in, but not required to access the information. Baby Centre also do really really good weekly emails for details on what's going on during your pregnancy and ideas for you to stay healthy and comfy. After baby's born they still do good weekly / monthly development emails giving you ideas of activities to do to at home to stimulate baby and information on what's going on with baby's development. They drop down to monthly if not less often once baby gets over a year old, but still nice to have a bit of outside advice for the kiddo.
On the Baby Centre (UK) forum they have a board with regular posters letting you know of any money saving tips:
http://community.babycentre.co.uk/groups/a285/money_saving_tips and they have an American ExPat Group:
http://community.babycentre.co.uk/groups/a941885/american_expat_group.
http://www.askamum.co.uk/ is another pretty good forum, though I must admit I'm not a big participant, but good informative articles there as it's from Mother & Baby and Pregnancy & Birth magazines. They also do pretty good weekly development emails regarding your pregnancy.