The method to get BMD (birth, marriage, death) certificates from Britain is not hard. You will need to have details on:
* Person's Name
* Year and Quarter of the event
* Registration District of the event
* Volume and Page Number
Having these details, which is known as the "GRO index reference" saves you pricey search fees.
Go here to find the record you need:http://freebmd.rootsweb.com/cgi/search.pl
In this case if you search on a birth for John Twigger, there is a likely match in Jun Qtr 1840 (that's June Quarter, which could be April, May or June 1840). You would ask for the certificate dated Jun Qtr 1840 for John Twigger, Foleshill Registration District, Volume 16, Page 398. This tells them where to look.
Use the same technique for the marriage certificate, just be sure to select the right Type of record when you're searching.
I always find it easiest to order certificates through the British General Register Office (aka GRO). Their website is:http://www.gro.gov.uk/gro/content/order_certificates/index.a...
There are instructions on that site for ordering the certificates. Once you're in their system it's easy, and in the past I've done it all via email. Having the GRO index reference info means you will pay 7GBP per certificate. Last I heard, the pound was about twice the value of the dollar, so we're talking about $14 per certificate.
Here's a shortcut to the order form, though I would recommend you go to the link above first and poke around so you have a better understanding of what you're doing:http://www.gro.gov.uk/gro/content/certificates/
You may sometimes be torn between ordering two records with similar details. Not sure if your John Smith was the one born in 1850 or 1851 in Podunk, Lancashire? If you know the parents' names you can supply those to help the person pulling your certificates get the right match.
I hope that helps.