I'm confused.
The 'thing' that you
can use on a Windows computer for accessing emails is called an email 'client'. (The equivalent on a mobile device is, confusingly, called an email 'app'). However:
(a) you need to have an email account somewhere first ; and
(b) you don't actually need those 'things' on either device, as you can simply access your email account via the provider's website .
It's not clear from your post whether you've already got an email account or not. I'll assume, for the moment, that you haven't. (Please post again if you have, telling us what comes after the '@' in your email address, so that we can assist you).
Go here:
http://www.gmx.co.uk/
Click 'Free Sign up'.
Fill in your details (including your preferred email address, which will end in @gmx.co.uk, and your chosen password). That's it, you've now got an email account.
To access your account at any time, go to the same link as above, click 'Log in' and enter your address and password. (When you've finished, it's good practice, to click on 'Log out' in the top right-hand corner).
You can use that method to access your email on both your laptop and your iPad. However you might prefer to use the iPad's dedicated email app instead. If so, see here for instructions:
https://support.apple.com/en-gb/HT201320
(If your iPad doesn't recognise the account automatically, use the 'Manual' instructions, choosing 'IMAP' as the email system and using the server settings shown here:
https://help.gmx.com/en/applications/imap.html )