With regarding to accepting credit cards. You first need a merchant bank account, companies like Lloyds and Barclays provide this in the UK.

Be warned though, it's not cheap to set one up, and you have to pay a percentage on the payments you receive.

To set up a secure server, simply use the link above for hosting, and you can also upgrade to a secure server for your pages which need security, or if you use a company like www.worldpay.com they will host this all for you, and deal with the credit card transactions.

The only thing I would work on your site is the font, the navigation and design of the site is fine.

Like the above poster said, Id work on hosting, domain name and then optimising your website before you take it the next step further.

Regards
Darren