Kerry is pretty much frost free in winter I think. With that polycarbonate would be fine. They are very popular in Germany which has much more severe winters and temperatures. The one thing with polycarbonate is that they need to be out of the prevailing wind. Mine is right up to my 6ft fence and protected on several sides. A neighbours is more exposed and his glazing is in next doors garden!

Polycarb also goes cloudy after about 10 yrs where as glass doesn't.

Hi Kerry,
Sometimes to be honest is'nt what people want to hear but its the best advice im going to give you and i only give advice on tried and tested things ive done,
So having said this and 3 greenhouses later here goes.
Dont waste your money on what may seem cheap no glass greenhouses, its going to cost you a lot more in the end,
These polycarbonate greenhouse's do not have the same weight when constructed and many bloggs have said that in the wind the glazings blows out, they're not a good re-salable item as they dont hold there price and this should say it all,
But more important than this is just ask yourself what seeds/plants need to grow,!
Light is one of the main things "good as clear as you can get light, the type of glazing used "polycarbonate" is'nt a clear material,
I was once a member of an allotment and one of the members had one and it was'nt worth the money and tobe honest you'd be better off with a polytunnel if your after cheap.
Take a bit of good advice "buy quality and buy once"
By cheap and buy again & again or get dis-hearted and give up.
Good solid glass house with a good solid base and your greenhouse base secured via good raxplug & screws to the base,
tip get a good wide door so you can get wide objects in and out with ease " window box's etc even a wheel barrow?
And make sure you've a few roof opening windows and as a bonus a side wall opening vent, all these you can get automatic opening devices for (these last for years easy to fit and dont cost a fortune)
hope this little lots helps

Just one thing, go bigger than you think you will need, because you will soon fill the spaces up!! That's my only advice.

"These polycarbonate greenhouse's do not have the same weight when constructed and many bloggs have said that in the wind the glazings blows out, they're not a good re-salable item as they dont hold there price and this should say it all, "

The cheapo ones in the UK can be like that, but if you pay £50 for it...

In Europe Polycarb ones are strong and double glazed makes them easier to heat than glass grenehouses and they hold the temps better.

Thank you all so much for replying. I have now found a company called Steeltechsheds, they say their greenhouses are built to last a lifetime and able to withstand extreme weather conditions. I tried to include a photo but failed.