My surgery does have a nurse (or nurses) who will take blood samples. Some surgeries may be too small or not have sufficient staff to take blood.
Taking blood samples is best done by someone who does a lot of them - I suspect that many GPs don't have much experience. In our local hospital (a district general hospital) blood samples are taken by phlebotomists, and that's all they do. They are specifically trained and sufficiently experienced they could probably get blood out of a stone. Also, they are good at getting blood out of tiny veins, and out of patients who are terrified.
kwini, the term "a cottage hospital" used to refer to a very small hospital in rural areas where the patients were looked after by the local GP. More complicated problems would have been sent to the nearest city hospital.
These days a small local hospital is usually linked to a district general hospital. There is such a "cottage"-type hospital linked to our district general hospital. Amongst other things, it has a minor injuries unit, day surgery for fairly routine procedures, outpatients department (the consultants travel from the DGH), some rehabilitation in-patient wards, and a small midwife-led delivery unit. There are probably no such hospitals in the London area, as these small hospitals are relatively costly to maintain, partly because they are small and often housed in very old buildings, and partly because in such a population-dense area such as London it makes sense to focus hospital health-care in specific locations.
Getting back to kwini's original concerns: there seem to be gaps in the advice given to people who ask the sensible questions prior to TTC but don't get a sensible answer. From kwini's experience, which sadly I doubt is unique, there should be some standards about advice/tests for those who want to prepare for the best outcome.
I know that Mumsnet is pushing for best practice in the care of miscarriages, so maybe this is a good forum for putting together good practice for people prior to conception.
(I would also love it if Mumsnetter could push for best practice for women approaching the menopause - when I asked my GP for advice about that all I got were some leaflets published by HRT companies.)