How do you intend to accept payment for goods? If you're only going to use your website as a 'showcase' for your goods, with payment being by post or by phoning you with a credit card number, then you don't need to worry about an SSL certificate.
If, as someone else has suggested, you accept payment via PayPal, you also don't need to worry about an SSL certificate.
However, if you intend to have direct online ordering (taking debit and credit cards), then you'll need to ensure that your site meets the security standards demanded by Visa and MasterCard. The big name, within the UK, for SSL certificates is Verisign. They charge �259 + VAT for a one-year certificate (with reductions if you buy two or three years at a time):
http://www.verisign.co.uk/ssl/buy-ssl-certific ates/secure-site-ssl-certificates/index.html
However, other firms such as ServerSpace, are much cheaper (�45 for one year, with discounts for 2 or 3 years):
http://www.theserverspace.co.uk/index.php?opti on=com_content&task=view&id=24&Itemid=45
You've also asked about web-hosting. FastHosts is used by many small businesses. Their packages
include SSL hosting (with certificate). The 'Business' package is �15.99 per month but, for small website, you might be able to use their 'Developer' package, for just �7.99 per month. One of the best things about FastHosts is that they've got a 24-hour phone helpline, which can be really useful to 'newbies' (and is much better than waiting days for other firms to answer their e-mails):
http://www.fasthosts.co.uk/hosting/
Chris