I agree with Wooft, Ric, about the bath.
A big mistake people make with B2Ls is they get too emotionally involved. When it's let, it's not "your" home.
Re-tile the shower maybe, but you need no more than a shower for a let.
Walk-in baths are a last resort for particular circumstances. It makes no difference to a let.
Only consider CH if...
You have gas
You're keen to improve for added value.
Storage heaters are fine for letting. It would be lovely to renovate the whole property to the sort of level that you might like, but often, the figures just don't add up.
Concentrate on maintenance, safety, and providing a good service to your tenants.
Oh............. and congratulations ;o))))