As others have said, the emphasis on lambing is simply in the ‘suggestions’ for work experience as it is likely a lot more hands on than other placements and teaches you a lot, especially if you aren’t from a farming background it is basically like a whole new world so it’s good to get started on it during your work experience. I always suggest to get work experience in each of the ‘categories’, i.e. smalls, equine and farm, as unis do ‘like’ to see it but it isn’t always necessary just to apply (though for example in normal years Glasgow does emphasise having farm and Liverpool asks you to have at least 2 of the categories) and it is mainly so you can see the differences etc which would help throughout the application process, e.g. more to speak about in interviews/forms as work experience is bound to come up in some form there. I also think it’s nice to learn the basics before uni, e.g. how to put head collars on, what animals eat, and just generally know you’re comfortable around the different animals so that when you do EMS on the course you can be learning other stuff - of course it’s not necessary though as that’s why you’re on the course, to learn, but that’s just my perspective so I’d say still go for lambing next year even though it won’t towards most unis requirements.
I’m not a great example I guess but I was a reapplicant for 2020 and 2021 after being unsuccessful in 2020, but I only managed to have a few days here and there of sheep farm work experience before applying this year and I still received an offer for Liverpool, and I got interviews at Nottingham (I also got an interview there last year with even less farm exp) and Glasgow so they clearly didn’t mind. I wasn’t able to secure a lambing placement for spring 2020 but I found a farmer after and I was able to go to a few random days like where they sorted which lambs were going for meat, so that’s still a bit of experience and then after I applied I continued to do some placements just for myself, e.g. went to sheep pregnancy scanning and I also did a few days of lambing. So you could still try to contact farmers about next year and any other events they’ll be doing, but lambing is likely over for the year now. Farmers also often provide accommodation if when it reopens you want to use the NSA website and have to travel a bit for a placement. But I’d really try to get some large animal experience like horses as they are completely different to smalls (though try get some smalls in too) and stables are generally covid safe being outdoors and love extra hands, so it may be easier to get.
Best of luck!