I put you on the mailing list for next month. What a shame about your potatoes. They will come back again though. There is no need to plant new ones or to plant in between. They are just going to be later. New shoots should appear within a couple of weeks.
In relation to tunnel plastic there is a big difference. A good source is Gillespie’s Polytunnels in Donegal. There really is a big difference in the quality of plastic. The one we received last year is covered with hundreds of little holes. The worst I’ve ever seen. So only buy from a reputable source.