If you can change your account to a PAYG account then you can still get at your email via ntlworld webmail from your new Tiscali account. You should even be able to set up your Outlook Express (or other mail client) to receive your ntl email, via your Tiscali account, but would have to use the Tiscali servber for any reply you send via Outloook Express.
However you may need to dial into the ntl account once every few months to keep it active
