Any advice would be greatly appreciated ... we have 12mm marine ply base in a 3mtr sq bathroom that needs tiling on a tight budget. from what i can see so far , the waterproof matting ( at £50.00 5sq mtrs roll ) plus joining tape ( £20.00) plus the additional flexi adhesive both under and on top of the matting almost doubles the cost of the project. Logically , unless the matting is seamless with a lip around all the edges and under the wall tiles , to stop any excess water escaping and rotting the walls etc, then am i right in thinking that the principal of waterproof matting underlay is null and void ???? PLEASE ADVISE, as i can't afford or want to sold into unnecessary costs

You may be able to fit a separate shower and bath in here, if that would be of interest. If you can find a bath that is 75cm wide (pretty standard), then you could put a walk in shower in the alcove where the towel rail is as the 50cm gap next to the bath should be enough to walk through. Gives a nice 125 x 80cm shower space. Alternatively as Jonathan suggests, build a false wall at the shower end of the bath to take the shower plumbing and screen, and try to wall off that alcove and access it from elsewhere so it isn’t wasted.

Can i give a shout out to the good old fashioned shower curtain. After years of wanting a bathroom revamp in what looks a similar sized bathroom to yours, I was delighted to have a sliding shower screen installed. It's two glass panels and swings out to clean the bath and for ease if access and does a pretty good job of keeping the water in. But I hate it. It's an absolute nightmare to clean and once achieved (with great difficulty and a mixture of scratch sponges and old toothbrushes) then keep looking clean. The gunge that builds up in places you can't see until you get your head under the bottom silicone strips is horrible and I'm constantly having to unscrew these to clean them thoroughly. If I could go back to a shower curtain, without damaging my tiles I'd do it tomorrow! I miss chucking it in the washing machine then buying a new one for under a tenner when it got a bit ratty or I fancied a new colour /style . I'm happy to try and find you the link (amazon if I remember correctly) if you're fixed on a screen because I think I chose the best I could have for my bathroom but just thought it might be worth mentioning before you go ahead with your bathroom update.

I'm also in the 'inset' camp. It should be big enough that you can get in, close the door, and 'arrive' (take off wet coat, shoes, etc) all while on the mat. It will be much easier to replace the mat if it gets tired than the area of wooden floor by the door.