Final (I hope!) conservatory question - heating

[Housemum]

Right, have decided no to underfloor heating (cost to install, cost to run) So the options are:

An electric panel heater, 2kW, would be £250 to fit

Run a radiator off our existing system, would be £450

Air con, worried this would be expensive/noisy, cost £900

Portable electric dimplex heaters that we have already (the wire element sort not the oil filled sort) cost nothing but could be expensive/inefficient?

The conservatory itself will be open plan to the existing living room and kitchen.

What have you got and are you happy with it/how expensive is it to run?

Thank you!

I've a radiator in my west-facing conservatory that frankly wasn't worth the hassle. I have polycool in the roof to keep the glare and some of the heat at bay. Cost- about 800 punds. Nothing under floor.

RAd have extra tiiny heTer for very coldest days

Think I will go with the rad as anything else (except underfloor) could be added later but once my nice new floor is down I can't rip it up to put a rad in.