[Closed] Best way to heat a conservatory (under £150)

Ok so an existing conservatory
Extending central hearing into it iod installing underfloor heating sn't an option for a couple of reasons
No full height walls
What's the cheapest in terms of running costs (electric) heater (ideally fixed but freestanding considered) that can fit under the windows
Don't really want to spend more than £150 must have a thermostatic timer

Looking to keep the chill off most of the day to and have it warm for an hour or so in the evening as we use it as the dining room, it's not a room we sit in for hours every evening

It currently has a small wall mounted electric heater that doesn't seem to kick much out, complimented by an oil filled heater that I would like to replace with something more permanent/more attractive