A lot of people who have had jetted tubs find that they seldom use them and end up removing them. If you are a devoted tub person, then consider a smaller soaking tub with no jets. The space you have allotted to your tub seems about a foot longer than necessary. That extra foot of space could be beneficial for a larger vanity or shower.

Another possibility would be to have a much larger shower and no tub, which is a popular choice in the US these days.

Yes the bath at present is way too big and is never used. We were thinking of a smaller/corner bath but not 100% sure where this would fit. The pen sketch is as it is now and we are cutting out different size fixtures to see where they fit and if possible to get a four piece in the space.

I would put a 6' vanity where the tub is now and enlarge the shower to fill the rest of that wall. Of course I am assuming that there is another tub somewhere in the house as you need one for future resale purposes.

That was our original plan but then we wondered if it was possible to have a 4 piece in that space.

I think a big modern shower with frameless glass will make for a better look and add value to your home. However, if you have concerns about eliminating the tub, I suggest you talk to a realtor in your area to see if this trend is viable where you live.