what size

What size does the squares have to be for quilting generally, and do they have to be the same type/thickness of material please.

The squares can be any size you like, Billie. Patchwork is traditionally done with cotton fabric, but you can use any fabric. However, if you plan to make something to use which you will want to launder, you should wash cotton or other shrinkable fabrics before you start, so that those squares don't shrink when you next wash the item. Fabrics which are too thick should be avoided, because of the number of layers which join together at the corners of your pieces, although you could get away with an odd piece provided it's surrounded by pieces of thinner fabrics.

Lynda

You can have them any size you want Billie, you can mix sizes/shapes too.
Fabrics, I think similar weights and types are better (especially for first go) but some people do mix them up to give more textured effects.

I made a cushion cover years ago in my innocence, used an old fabric and 2 new fabrics. The old fabric wore away but the new fabrics remained intact. Just make sure all the fabrics are similar weight, have a google or look on pinterest, you will see that there is an endless variety of designs and patch shapes.

Thank you all, if I do anything thats in my brain hahaha (what brain do you say) I will show you it but that could be months away

We look forward to seeing it, however long it takes, very therapeutic and addictive, patchwork.