Website optimised for mobile phone

General information for the website: Need a one page website more like a contact form which has to be optimised for mobile phones. Have brought the domain names , not found a hosting company as of yet, so any advice on that front would be appreciated. Have all the content and can provide a sample webpage to copy in effect .
Kind of development: New website from scratch
Num. of web pages/modules: 1
Description of every page/module: a short title and contact form
Description of requirements/features: contact form with 12 boxes
Extra notes: I need 3 of these websites doing, I have the domain names brought through 123-reg, but have not brought any hosting packages as of yet, any advice on this front would be appreciated, do i need to buy the hosting first so you guys can build the website on their website builder or do you use your own programmes ? If own programmes can it be done on one that is popular with the service providers?