Attic balustrade (banisters/railings) in terraced houses

Can anyone advise on what to do about renovating the balustrade that is in the attic in small Victorian terraces? Mine is what I take to be the original (as I've seen similar ones in other old houses of this type) but it's just a rudimentary wooden structure made out of two narrow horizontal rails fastened to two basic newell posts. The horizontals continue at right angles and are fixed into the wall.

As it's 'an original feature' there is no immediate need to renovate it, but it's not very attractive, practical or safe. The top rail is too low by modern standards and there are massive gaps where a child (or anyone) could fall through and down the attic stairwell.

What are my options and ideas of cost and presumably I'd need building regs approval?

I imagine there are at least three options:

1. Replace with Victorian-style spindles and rail to complement the one on the first floor (I doubt it's worth the expense on this option)

2. Extend existing and fill in gaps with similar simple lengths of timber.

3. Very basic repair just to make it safer in the interim but which could be removed to leave the original at a later date

Thanks

hi the building regs for a stair case in for a 900 hand rail . and the spindles no less than a 100mm between the next kind regards jeff i always set mine alittle higher for handrail on landing ta jeff