I've decided to buy a greenhouse but never having had one would like your views on what to get

Firstly, get the biggest greenhouse you can, because you always run out of space!

Secondly, I'd personally go for glazing, rather than polycarbonate. I haven't had the experience myself, I admit, but I've seen (and heard of) this material being short-lived, going brittle, developing holes and coming apart.

I made mistake no. 1 and got a 6' x 8' which was soon full to bursting. I now have a second one! I'd advise you to check prices both on-line and in your local DIY and GCs, as they vary so much on the same product. I saved at least £150 doing that. :-)

Thirdly, do get electricity installed - you won't regret it! It's important for such things as heating and a propagator.

Thanks Spritzhenry- don't have room for much bigger, may squeeze an 8 x 8 in. Electrics wont be a problem, that's my trade! Much to think about....

Like Spritzhenry, I would also advocate glass unless you have children. I started with one 8x6 then added a second. I now have plants in a neighbours across the road, all aluminium.
Think about the floor as well. Concrete is relable but expensive and you can only put things 'on' it. Hard packed soil gets messy. You could use gravel on hard packed soil. My best floor has soil with 12" slabs laid on it. I have benching on one side and a path in the middle. On the other side I have removed the slabs and have built a plunge bed. You could grow taller greenhouse plants directly in the soil.

I have a slabbed floor, as I don't grow anything in the 'borders'. I have benches along each side and across the ends, plus hanging shelves - and I still manage to fill both greenhouses completely! lol.

You'll need at least one automatic roof vent, plus a louvred panel at the end of the greenhouse. That really helps the ventilation. I use my fan heater to cool the air in the summer if it gets hot.

I too had a six by eight and wished it was bigger - I would go for the eight by eight if you can, and yes go for glass. A fan heater on a frost setting is a good option as it keeps the air moving.
Insulating with bubble wrap saves a lot of heating.

Thanks for the advice folks. My kids are grown up so glass would be ok- thought polycarb was better in winter though? Was going to plant directly in the ground with some staging for pots. Any brand recommended? Many reviews I've read are mixed with people slating poor instructions.

The first lot of staging came with the greenhouse - a special offer. My other staging is partly from B&Q, and partly made in wood by OH. ;-))

Why did you think polycarbonate was better in the winter, by the way? That seems to be the time when it goes brittle, so I'm told.

this site has a good variety to choose from.

http://www.greenhousesdirect.co.uk/Selector/6x8/

Local "chippy" could help bring down price of timber frame, just a thought.

If the site is windy or exposed, make sure there is sufficient bracing (diagonal pieces) in the design.