Sealing tiles, grout and wall

[vipt]

Hi, I am seeing issues with water through wall and floor under the bath. As an explanation, it is a large P-bath with large tiles and large grout lines, but used as a shower mostly. The tiles only go down to the bath, so under the bath it is just bare walls. I plan to try and fix this by sealing the walls under the bath, sealing all edges with silicon sealant and sealing tiles/grout with something.
I'm looking at a budget solution but the most effective so there is a trade off. I cannot afford to strip tiles and redo them, or cut the grout out/regrout as I don't think that's going to fix the full issue.
So I thought about SBR or PVA for the walls but that led me to lots of posts that say don't use these near grout. I also wondered if SBR/PVA on the grout/tiles but again the posts tell me this is not a good idea.
Can anyone tell me from experience what I can do here, I don't think there was any coating on the floor/wall before tiling so I need to get as waterproof as possible. What to use on the tiles/grout, what to use on the walls that is both efficient and budget friendly? I was thinking initially a bulk can of something (like https://www.screwfix.com/p/thompsons-water-seal-clear-5ltr/52043 if not SBR or PVA).

Any help will be appreciated.
Thanks

 

[Wayners]

Water can get around shower mixer if piped through wall or any drilled holes. Seal around with clear or white polymer like CT1 or stixall.
Get under bath and stick wood battens to wall packing up tight at the bottom with polymer grab like stixall. You can make them T shaped.
This will stop any flex in bath edges breaking seal and leaking.
Dig out any problem areas and regrout.
Maybe look to clean old grout and use a grout sealer.
Dig out silicone and clean edges with meths then put a good tooled angled bead of silicone around the edge of bath. Don't use finger. You need something thickers and angled.
Charliediy on YouTube has great videos on this.
With good sealed grout.
A siliconed bath that don't flex you won't get any water passing.
I don't understand why your messing under the bath as your should not be getting water under.