This answer is relevant if your website has been designed and built by BT. View FAQs for Web Hosting if you built your website. If you're not sure which website package you have, please read How to get support for your website.
Regardless of which development project you take with us, you will own your website and have full access to all areas of your site.
To change the design and layout of the website you'll need some basic coding knowledge, if you are comfortable with this, there's no reason you cannot update your website's template yourself.