Our shower cubicle is tiled and we want to paint over them. Which is the best paint to use please?:

What kind of tile do you have? Bath wall tiles could be ceramic, porcelein, plastic or even tin. I assume you want to paint them because the grout looks bad or the color is hideous. Right?

Yes you're right - the grouting looks hideous but also it kept leaking and we couldn't find out exactly where so we're being lazy and thought if we got some really strong paint which would make it look better and also seal the leak, that would work. The tiles are ceramic. Cheers

If you have a leak with ceramic it isn't always the grout that allow the water to leak. A properly installed ceramic tile wall can be water tight with no grout at all. You may have a leak at the mixing valve or along the tile edges where they meet the inside corner on the wall or at the point where they touch the tub. All the paint in the world may not stop those leaks. Lets get the leak fixed first and then decide about the painting. Tell us more about the leak, where exactly do you see water and under what circumstances does it appear?

After you get all leaks fixed and still want to paint, Zinsser B.I.N. is the best... Sticks to everything... heres a link to the product.
B-I-N Shellac Base Primer Sealer (http://www.zinsser.com/product_detail.asp?ProductID=10)

There is a product used to stain and seal existing grout that would work better for you, painting ceramic tile is not adviseable, it will eventually peel. I agree with ballenger, I think your leak is being caused by something other than your tile. As he said, let's figure out where the leak is first.

Grout Stain (http://www.super-tek.com/groutstain.htm)

If you are still set to paint then I'd recommend Rust-oleums Tub and Tile paint. It's a 2 part epoxy and will stick to clean ceramic, no BIN primer needed. You'll be light heade for awhile without proper breathing equipment and you can use the shower for 3 days after application. Did you ever find your leak? It does sound like you have 2 issue; aleak and hideous looking tile.