When I'm using the keyboard on my iPad 2, as I get lower down the screen, the keyboard hides the text, and I have to press the hide keyboard key to see what I've written, then have to write blind to continue.. How do I correct this?
It has only happened in the last few days and I haven't done anything different

In which app, Safari? If it is Safari, which website?

Can't you just scroll up the page using your finger on the upper part of the screen? It could be the website that has changed.

Doing a reset of your iPad by holding down the power button and the home button (the round one on the front) is always a good first fix.

Its when I am replying to emails, or filling in a contact form on a site.
I use Google as browser
This is a recent thing