Question about contact form

I would like to bring up a contact form when users visit my site.

On the form, I would like to ask them if they would like a free guide sent to their email address. If they agree, an email would be sent to my email address with the request. Then I could send the guide to them.

I have been doing some investigation and it sounds like lots of businesses use this sort of thing (email marketing) – I am not trying to make any money, but I would like to be able to do this on my site. So I did some more searching and found 2 ways of achieving the desired result….

1. Use a WP plug-in – there was one called “Custom contact forms” which looked like it would do the job – but I am not 100% sure. It is not obvious from the documentation or…

2. Use a 3rd party tool eg mailchimp which looks like it does something similar. Then somehow embed the code/form produced to my WP site.

Or maybe even a combination of the 2 ?

I would love some advice, as I am sure this is something lots of people have done before, but its very difficult to find exact information on the best way to go with WP.

Thanks in advance for your help

Ian