The plants will be fine in a green house... They will be perfect in a green house ! The greenhouse stops them from getting wet. This almost 100% prevents mould.

just be sure it doesn't get too humid in the green house. Let some air move around. Let the plant outside the green house sometimes in the first 6 weeks to help to train it. This help the plant to develop a strong trunk and strong branches. This is important for when the buds develop.

I would have me seeds planted by now if I were you. If you get down 10 you will be done for smoke for the year.

Have a look on the Rhino Seed company website. I just picked up 10 Mataro Blue Autoflower feminised from that site. 100% germination and they are all outdoors now ! 75g average per plant.

Just get the seeds germinated between some damp kitchen roll and get them in individual small pots.

Get them in the green house after they sprout. You need to get a move on. The last frost is when they are normally planted, late March or so.

You can plant now. It's no problem. The plants won't begin to bloom until mid August or so. So you have from mid June, all July and August to veg them.

Just get started and it will be easy to point you in the right direction as the grow progresses.

Best of luck mo chara