upvc or horticultural glass?

My own personal experience is that glass is far better.
The greenhouse doesn't blow away in the wind.

I've had a Norfolk greenhouse with polycarb glazing for 4 years now. A few of the 'panes' blew out in a gale the first year, (obviously they didn't break) so I fixed them all back in with sealant and it's been fine since.

Fixed to the base exactly the same as a glasshouse it shouldn't blow away.....mine hasn't

I've no experience of the Norfolk ones that are a standard greenhouse frame but covered in upvc soft sheeting, though, if this is cheaper kind that she's been looking at