when in Thunderbird and I click on some link to go to a special offer or something etc, nothing happens and it returns to that same email message rather than open a new window or tab

That's usually because you're viewing a message created in HTML format but the link is not properly enclosed in tags that indicate it's a clickable. Thunderbird can often recognize that it's a link but it's not infallible and it errs on the side of caution because some spam and other malicious emails can obscure the true destination of the link and it may not go where you expect. When you're presented with a link it's a good idea to hover over it before you click and note the actual destination in Thunderbird's Status Bar

When I get a message like that, I can usually get the link to be clickable by viewing the message in Plain Text format. See menu option <View | Message Body As> and choose "Plain Text".