Tiling a quadrant shower enclosure

Hi all,

I've been tiling a 800 x 800 quadrant shower enclosure that I just put in with a handyman.

The tiling for the previous enclosure was just done over plasterboard on one wall and plywood on the other, so we did the same again. (I wasn't aware of cement/waterproof boards at the time). However we used waterproof tile adhesive and a decent quality grout (http://www.toppstiles.co.uk/tprod44012/section173/bal-micromax2-white-25kg.html) - although not epoxy grout.

Is this good enough to stop the water or should I get some grout sealer or re-tile over a waterproof board?

I'm also worried that the enclosure was screwed into the wall and then the tiles were done, rather than tiling and then installing the shower enclosure. Is this a problem?

Thanks for the advice,

Matt