Thank you all.
There will be no underfloor heating, the towel rail radiator does a good enough job.
We already have an extractor, so that's sorted, ditto the hooks on the back of the door.
So, in theory it's a relatively straightforward job 
Remove tiles, bath, vanity unit, toilet and existing shower.
Put in paneling, new L shaped bath (1600mm length) new washbasin/wc combi unit and possibly talk cupboard thingy (the wc we have chosen is square
, just hope we don't have to have our bottoms adjusted to fit it!) shower, taps etc. The shower might be a challenge, could need a pump, but final decision not yet made.
Then once that's done, decide on new flooring, dye towels and bath mat.
After that, spend time thinking that perhaps that other flooring/paneling/shower etc just might have been the better option.............