[cc]

Can I split this or do something with it as it's now blocking the light from other plants to its right.
I have already removed some of the stalks so it is actually taller.
As in the picture.

[mumofstig]

They are usually split during the dormant winter months. I think you may struggle to keep it alive if you do it now, especially if we do ever get any hot weather 

[Christine]

I'll second that mumofstig

[cc]

When I split it I assume I can leave half in the ground and move the rest somewhere else?
Midwinter?

Thanks I will add to my reminders

[Aunt Sally]

February is the best time for splitting rhubarb. 

Dig it up and remove as much soil as possible.
Chop it into smaller pieces with a spade.
Leave it on the ground to be frosted before replanting.

[Aunt Sally]

John’s advice here : 
https://www.allotment-garden.org/fruit/rhubarb-growing/

Quote:

• Propagating rhubarb is easy; when dormant from late autumn to early winter, choose a plant five years or older, dig it up, split into three vertically with a spade and leave on the surface to allow the crowns to be frosted. In early spring, as soon as conditions allow, replant. Discard any rotting or soft spots.

[cc]

Thanks all